Have it rendered both ways so you can see. I can't imagine 12' ceilings everywhere -- can you?

I'd say 12 on the first and 10 on the second.

It seems like if you had proportionally tall windows on the first floor, the exterior would look fine. If all standard windows, then the difference would be much more noticeable.

If most of your first floor is living spaces, a a higher ceiling height would give it a more spacious feel. A 10'x10' room feels much more voluminous when its 10' or 12' v/s 8'. Remember added height affects your construction cost as well because now you have an extra 20% which you will have to insulate and also heat and cool.If the second story is primarily bedrooms you could econimize by maintaining an 8' plate height. The windows should not be a problem.

The second floor is only bedrooms so that is why we only wanted 8' on the second floor for the more cozy feeling. We were worried there would be too much space between the downstairs and upstairs windows when looking at the house from the outside and it would look odd and disproportionate. Thanks for all the advice!

You would change the window and door heights if you went from 10' to 12' on the first floor.

it should be fine, but that is in the hands of the architect. bad design can make any amount of $$ turn out poorly.

as far as 10 or 12... where do you live? in a hot climate high ceilings are wonderful. in a cold one, you'll never warm up with high ceilings, and i'd keep it in the 9-10 range.

if you can do so, having 8 foot ceilings on the second floor, but vaulted in the master bedroom, will be a good compromise for coziness, economy, and grandeur.

IMO 12’ ceilings are just plain waste of space and provide no real bonus except huge heating and cooling costs as for bedrooms why a 10’ ceiling in a space that should feel cozy and induce restfulness has never made sense. I would do 10’ on main and 8’ on upper

Highly recommend starting, first, with the rationale for your decisions: why X feet here, Y feet there?Variables include items others have expressed (construction and ongoing costs).

Key is your thinking behind the "why" of all aspects of your new home. If building, you should know the answer to questions you have yet to imagine. You may come down to "this or that", but it will be YOUR this or that, not a contractor or tradesperson "we've always don it this way" solution (which is often not what you would have chosen).

Start imagining--someone decides every single aspect of a construction and you want to either make those decisions personally or understand and trust someone who will. When in progress, require timelines for ordering so that your decisions are not rushed. They will be--so your advance planning is a critical foundation.

Good luck - enjoy!

Our dilemma is not just with 10 versus 12 foot ceilings for a 2 story structure rebuild, but dealing with antique Dutch chandeliers that take up any where between 3 feet to 5 feet in height on their own. What to do?