A formal dining room is going to need a chandelier that hangs fairly low over the table. It’s also an item that is pretty style/taste specific. I’d just put up an attractive flush mount ceiling fixture now and let a future buyer pick a chandelier if they want to use the room that way.

For occasional adult guests (no more than several times a year), consider investing in inflatable mattresses. Then sparsely decorate the room so you would have room to inflate the mattresses as needed. If your guests will mostly be children, a large thick gel mat on the floor and a sleeping bag could work for them. You might consider built in cabinets on one wall within which are a pair of Murphy beds. If the room has a vaulted ceiling or the height is sufficient (more than 8'), you might consider adding a loft. Unless you actually don't like your overnight guests, you shouldn't even consider trundle beds or cheap "day beds" as the mattresses are usually really thin and very uncomfortable for anyone weighing over a toddler's weight.

I've used THESE 900 lumen, 6", 3000K lights with good results. I normally center the lights 36" from the wall and put them on a dimmer switch.

@cpartist The back of the house faces north, so it should be steady light while the sun is up. Not sure it would be worth the magnitude of floor plan changes. Are you in the southern hemisphere? If not, then the house will actually be quite dark since what you want in your public rooms is southern light, not northern light. I know you're set on this plan but here is something I continually post for others. Anything in bold needs to be really thought out regarding your plan. The best houses orient the public rooms towards the south for the best passive solar heating and cooling The best houses are L, U, T, H, or I shaped. The best houses are only one to two rooms deep. And covered lanai, porches, garages, etc count as rooms in this case. The best houses make sure kitchens have natural light, meaning windows so one doesn't have to have lighting 24/7 to use the kitchen. (And no, dining areas with windows 10' or more from the kitchen will not allow for natural light.) The best houses make sure all public rooms and bedrooms have windows on at least two walls. The best houses do not if possible put mechanical rooms, pantries or closets on outside walls The best houses do not have diagonal interior walls making for odd spaces. The best houses keep public and private spaces separate. (look how you get to bedroom 2 for example. The best houses do not have you walk through the work zone of the kitchen to bring laundry to the laundry room. (Most laundry is generated in bedrooms. Look at the path to the laundry room from your bedroom.) The best houses do not have the mudroom go through any of the work zones of the kitchen. The best houses do not use the kitchen as a hallway to any other rooms. The best houses do not put toilets or toilet rooms up against bedroom walls or dining areas. The best houses do not have walk in closets too small to stand inside. The best houses do not have roofs that are overly large, and dominate the exterior of the house. The best houses do not have stick on exterior materials only on the front façade. The best houses have an organizing “spine” so it’s easy to determine how to get from room to room in the house and what makes sense. Meaning they don’t have meandering circulation paths. Honestly this is not a very good design and especially not with the rear of the house facing north. I'm wondering if another of the plans might better suit your family.