The question isn't about how the house should be built, the engineers ARE designing that (and it's very conventional building). The question is, how much of the beam do I want to SEE when the ceiling is finished. How much of the 12" beam should be above/below the drywall? The raised eyebrows are due to the fact that I want to see the beam, not that the beam needs to exist. They assume that a big open room with a flat ceiling is better. But to me, it's less character. I have a choice, based on the engineer's options, to have a 12" beam with joists sitting on top of it, or a 12" beam with joists attached to the sides with joist hangers, or a 12" beam with the joists on joist hangers but they sit higher than the bottom of the beam. On the second floor, the beam is flush, and the joists come into the side. In the basement, the joists were on top, but when we asked about options to make the beam higher (dig the basement deeper? use a steel beam?) it was suggested that we go "semi flush", allowing for more head room, but still allowing for room above the beam for ducts/pipes/wiring, etc. So, which way do we want it on the main floor?

Is it correct that these are "decorative only" beams, and serve no structural function? If so, then ask your builder to give you architectural elevation drawings of the space both ways. Then see what you think. I also recommend that you find a copy of the book by Architect Sara Susanka called the not so big house. I say that because there are a lot of contemporary and well designed homes in the book. You can see what you think when you see them. Her book also discusses how spaces that are too large can feel as though they are too formal and lack intimacy. Since it sounds like you don't want to be too formal, I think you would get a lot out of this book.

how many is relative to the room size and the room's function. get 3k if that is what you like.

I'd roll with with a lighting designer suggests I think you could pull off 2 (in the center) or 4 chandeliers here, depends on how the room will be furnished. I'd think about 8 can lights as well, and sconce lights depending on the other finishings. Put everything on dimmers - you can never have too much lighting, but you'll kick yourself if it isn't enough or if there is shadowing. How do you intend to use the room?