We went with 10 foot ceilings and it feels pretty tall. If I could do it again, I might do 9 foot ceilings, but that's just me. My old house had 8 foot ceilings on the 2nd floor and they felt way too low.

We have a similar plan at 15' X 41'. Our ceiling height is 9'4", and seems about right. The odd dimension is due to the ICF forms that the house is built from. I plan a coffered ceiling in the DR, but haven't gotten that far yet. Our space has a large cased opening between each 'room' to break up the huge room a bit. The opening is smaller than the room by 20" on each side, and 16" from the ceiling. The pic is looking toward the kitchen.

We went with 9' ceilings and used a soffit in the shape of the island to visually separate the FR from the kitchen without creating an actual wall.

We went with 9' in our new build open concept kitchen living dining and I really regret not doing 10'.

I think we are going to go with 9 foot ceilings throughout. We don't want a 2 story great room, but would like to bump up the ceiling night in that room. What is the highest we could go without affecting the rooms above?