Generally the dining table is closest to the kitchen and would be centered under the light. Is there going to be a TV in the room? That will effect furniture placement. Are you seating a lot of people often? You could do a rectangular table that could be used as a desk and add leaves when necessary.
Can also cap the hanging light, depending on your other lighting sources, if the location doesn’t work.

I am seating a lot of people often. The will not be a tv in the room. There is barely any lighting at all, it is something that needs figuring out.

The dining/living section is about 28ft long. Dining is around 20 ft wide and the living has that extra peice so is around 25 ft wide.

Adding recessed lighting and eliminating overhead lighting will give you the flexibility you need. If you put a table where the current dining fixture it would allow you ample space to work but may not be big enough to accommodate a very large group with leaves in the table. You could flip the table the other way so it is going into the LR only when needed or all the time. I’m not a fan of looking at the back of a sofa unless the room is very large. Depending on what other furniture is in the room, I’d put the sofa along the back wall or in front of the windows. This would also allow the table to “spill” into the LR if necessary.
A mid century sideboard would be great on the wall in between. I’d use an area rug to define the LR seating area with 2 accent chairs and a coffee table.

Seating 6 at the dining table is usual to a maximum of 8.

As far as work space 2-3 people with laptops & papers all week is usual. That is why we probably have to go with a rectangular table. I measured for clearance and it seems maximum length would be around 78" long, legs might make it feel tighter to sit unless it is a pedestal. A round table would be easier to walk around but probably not conducive to double as a work space.

In the living room I would like to accommodate the same 6-8 comfortably for conversation.

We could do any changes to the lighting without issue.

I think you have to do a rectangular table given your parameters. A 60” table would be ok for 6 people eating but might be tight for 3 people to all work there. Get a table with leaves. They vary in size but are usually 12-18”. Depends on how much “stuff” people have in their work area. Would you consider adding a desk that could go against the wall? Could be more streamlined and console table ish and could do double duty as a server if needed.
Sectional could work for you to accommodate more people. Could also do a larger sofa (though still realistically only 3 people can sit there) and numerous chairs. Would depend on size of chairs as to how many would realistically fit. Stay away from a loveseat as it limits your options both with moving it around and number of seats.

You can create a buffet-storage unit on the wall of the dining room office that allows for both stashing away laptops, papers, work stuff, etc and also, if you like, has pull-down desk space.

Création et réalisation de mobilier sur mesure · More Info

If you like modern, one fun thing you could do is get office chairs on wheels to use as dining chairs. These are all inexpensive

ACME Yoshiko Swivel Adjustable Office Chair in Black · More Info

Safavieh Ember Office Chair · More Info

Poly and Bark Alva Task Chair in White · More Info

Or if you get lightweight plastic chairs, you can easily have them doing double duty in the living room, moving them as needed for guests.

Set of 2 DAW Red Mid Century Modern Plastic Dining Armchair, Wood Eiffel Legs · More Info

Your dining table is likely to be your biggest expense, but don’t forget the option of buying a sufficiently long table top and putting legs on it

Multi 71" Table Top With Trestles, Top: Walnut, Legs: Black Lacquered Steel · More Info

Switching out the hardware on your kitchen cabinets and the lighting there would get the kitchen moving in the direction of blending in with the rest of the decor.

You can find loads of inexpensive modern living room furniture that looks great.

Some fun lighting for over a modern table between your living room and kitchen

8-Light Black and Chrome Exposed Bulb Linear Chandelier · More Info

Modern LED Linear Chrome Chandelier · More Info

This isn’t fun but it could be very attractive. Click on the info link to see pictures of it used in a dining room

Canarm LCH133A48 Jaco 47-1/4"W Integrated LED Linear Chandelier - Black · More Info

Elan Sava LED Black With Chrome Linear Suspension Pendant/Chandelier · More Info

Woodbridge Lighting Vento 5-Light Linear Pendant · More Info

Woodbridge Lighting Vento 5-Light Linear Pendant · More Info

I think it also comes in gray

My mom had a large great room for dining/living, and had her couch separating the two. She finally allowed me to move the sofa to the side wall with a couple chairs across from it and it looked way better! Without that "divider" the functions of each space could be extended as needed for company. Also, the sofa no longer blocked the light crossing from the living to dining areas, so the who space looked much brighter.

So try not having the sofa cut the space in two... It doesn't need to be right up against the wall either - especially if that creates too much space between the sofa and chairs. Keep the space conversational and intimate. That can be a challenge in open floor plans...

What fun to be starting from scratch. You have a great space! The dimensions you have given are quite a large space so space for what you want should not be a problem at all. If the DR & LR space is 28' on that long wall and then the rooms are 20' DR and 25'LR you are in good shape. I suggest you carefully measure just to be sure because in the photos it doesn't actually look that large.

Start with an inspiration piece to get your colors. This might be either a very large piece of art for that far wall, or a rug, or piece of upholstered furniture. Then build everything else around it.

You ought to be able to find a used MCM rectangular table that is plenty big (as others have said a 60" table would work for 6 to eat and 2 to work, but you have space for a larger table so I would get a larger table to easily accommodate 8 to eat and possibly 3 to work). The modern rectangular chandeliers posted by someone above would be great in this space. On the wall opposite with window you could put a buffet or a credenza or whatever is most functional for your lifestyle.

For the living room, there are several ways to seat 6-8. Do not get a sectional. They work great for TV watching by a family, but not for adults having a conversation. A sofa flanked by 2 chairs on either side (4 total) is comfy for 6 and then you could have 2 cube benches opposite the sofa if there are 2 more. Another option is 2 opposite love seats and then 2 chairs and again the 2 cube benches. In terms of orientation because your room is so large you could try the sofa under the window or rotate the seating around to see what you like. Then fill in with several side tables, a coffee table, and LOTS of lamps. A rug would anchor all of this. For your budget sisals are nice and trendy. Get at least a 9'x12', but again since your room is so big I think you could go even larger to say a 10'x14'. Keep the furniture mostly on the rug away from the walls and you will have plenty of all around room.

For work from home spaces, you have space to add a desk to the LR for the third person, I suggest in the corner right by the foyer.

Good luck.

Fun replacements for your kitchen fixture

Sailee LED 3-Light Pendant, Brushed Nickel Type LED Panel 10Wx3 · More Info

Kichler 16-in Modern Orb Brushed Nickel Indoor Ceiling Fan and Remote · More Info

1-Light Chain Hung Pendant with Square Fitter, Matte Black/Pearl Ebony Art · More Info

Thomas O'Brien Gale 1 Light Flush Mount in Bronze · More Info

Thank you Ital mover for all the great ideas you took the time to find. I am thinking the office as dining chairs might be very appreciated by everyone using them all week.

I am really considering what will work better for couch placement. I like your idea msrmom to first get the seating peices and play with placement then purchase the coffee and side tables after it is setteled. Maybe I can just get a couch in there first and use some boxes and chairs to visualize things.

I measured the living room area again and an 8x10 rug will be too small but I think 9x12 or 10x14 both would work. If they both work, which looks better?

Go for the 10x14. It ought to be 1' off all the walls, plus allow space for walk ways. Here is a link to a basic rug that would go with everything.https://www.homedepot.com/p/Safavieh-Natural-Fiber-Beige-10-ft-x-14-ft-Indoor-Area-Rug-NF447A-10/205712961

First get the bare bones of the room right, by taking curtains off the windows, changing the paint color, and replacing the two ceiling fixtures. Leave the kitchen as is. If budget is a main consideration, purchase the ceiling fixtures at IKEA, which also has a terrific inexpensive midcentury modern sofa, the MORABO series, in either leather or fabric.

I got the rug, I have it unrolled to flatten the curled edges.
I want to do the curtains next. I do not know how far to hang them overlapping the wall. Right now you see only 3 panes, but the window has 5 panes width. What do you think will look better? Overlap the wall a little or go wall to wall?

So exciting. What size rug did you end up getting? It looks great with the floors.

That's a good question about the curtains. There is still a lot of wall beyond the windows so I think enough curtains for the entire wall would be costly, But if you can afford to do ceiling to floor and wall to wall and then open them to uncover the entire window it would be a clean modern look. However, if you just stack them on the wall, but don't cover the entire wall, I think that would be nice too. If you are buying panels make sure there are enough that you could cover the windows if you needed too and that they look full when stacked. No less than 2 and perhaps 3 panels per side? I'm guessing if you want to cover that whole wall you might need 4 or 5 panels per side. Thats a lot of panel! If you can find extra wide ones or have them custom made that would be preferable. Rule of thumb is 2x to 3x the width of the actual window - more with a lighter weight or unlined curtain and you can get away with less if they are substantial. The ones left by the previous owner are insufficient.