Open concept home with 12' ceilings and vaults will be loud! And difficult to cool down and heat. What kind of climate are you in? What about hard surfaces...is it tile, stone etc...just wanting to point out the echo and the need for lots of rugs and curtains you might have.

I have 17’ vaulted ceilings In my living room and kitchen and there are no echoes. I live in the greater Seattle area so we don’t worry too much about air conditioning but I don’t find it hard to heat our home either. The greatest hurdle for us has been adequate lighting. It is definitely expensive

We live in Texas. Its just hot all the time (which we love). Thank you for bringing up the cooling and echo. It will be hardwood floors. I am not so concerned about echo, as we only have one kiddo so not too much commotion going on in our house. Our current home has 14 ft ceilings in the main area and I think its too low. We will have either windows or window slider doors on the backside of the house so lighting shouldn't be a problem.

noise depends on what you mean by open concept. our kitchen and living room are all one room, so I think of that as open concept, but our bedrooms are down a hall. therefore, we don't have noise issues with sound from the living room.

when it comes to heating/cooling, it depends on the engineering. how high are the ceilings? how much insulation? how big are the windows and what way are they facing?

all of our ceilings in the whole house are vaulted but not super tall (about 11'). we don't have much of an issue with heating in the winter, but the living room is really hot in the summer, mainly due to the fact that it's not in the shade and has big south facing windows (this is Seattle, where it rarely gets over 90 deg). we had 6" of rigid insulation installed under the roof, but it's not nearly as good as having an attic with blown in insulation.

I love vaulted ceilings and would absolutely have them again, but just be sure your architect is considering the best when it comes to wall, ceiling and window insulation.

finally, other noise factors to consider: we have a metal roof. so that plus no attic means we can hear everything that hits it. rain? very pleasant. pinecones hitting it in a windstorm? SO LOUD. the last time it happened, we barely got any sleep. of course if you have a shingled roof, it won't be as much of an issue.

What does the person designing the house recommend?

she just asked if we wanted the entire living/kitchen area vaulted or just the living room.... I was stumped. as of now, she designing it as vaulting the whole area, but Im questioning whether that might be "too much" .... Ideally I like clean lines and even feels throughout the house but that changes when it comes to ceilings. I do like different heights based on comfortably. We are leaning towards high ceiling in kitchen and then vaulting the living to give dimension and transition?

I have a 10' ceiling in my kitchen and family room, dining room with a 12.5' vault is separated from that space with a partial wall. I love having the visual separation created by the varying ceiling heights of the vault, tray (kitchen) and flat (family room). It's more interesting in a large space....I also have 4 kids hence I mentioned the increased noise level ;)