Just put an addition on my house as well, and it looks very similar to yours, only I have a front porch. Because my house has a hip roof, we were only able to go from an 8 to a 9 foot ceiling for the back addition. Otherwise, it would have looked weird in the front of the house. Your architect will be able to help you with that. I would go somewhere from the front door to that walkway between the garage with the addition in back. I'm not a pro, so don't take my word for it....but I think the placement of the roof lines with that area will make the most sense. You'd be surprised what an update it will make! Lucky for you, your garage is in line with your house.....my was at an angle and made for a VERY tiny laundry room coming in from the garage, but it's just the two of us now and we will make it work. I could only make my addition 20 feet wide because of the angles of the different roof lines and hip roof. It doesn't appear you have that problem, so could make a fairly large addition out of it! I'll try to attach some pictures of mine to give you some ideas of how it transitioned into my roof line. I, too, have two entrances like you. One we use the heck out of, the other one just for moving big things in and out of the house! LOL!!

@thinksesignlive...that’s a great image. Do you think the wood slab ceiling would make the space darker further and make the ceiling feel even lower? What do you think if the wood seat ceiling had slats of mirror randomly incorporated in the space? Then on the floor which which could be wood slat as well, but incorporate random pieces of a heavy duty frosted glass (the feel of a water element) in the space. Instead of a couch for entertaining guests, incorporate outdoor patio furniture but more lush but durable cushions (sunbrella fabric). Maybe just a couple tall low level light plants, use a plant service to change them out every couple months. Lastly, add a simple zen water feature so block road noise and bounce light off of in the evenings. Movement in a space adds life to it,

What will you do with the interior stairs? An easy entrance would be to move your door to the garage to the foyer, maybe recessing the closet into the library. Then, close off the hall to the basement door hall, or put a door locked fom your side. Replace that window with a door, and your tenant has their own entry.

Here’s the pictures of actual space. The corner is where Vacuum is on the picture. Thanks in advance.