It gets pretty dang cold here where we live. When we put down tile floor in the main part of the house, we had a heating element added ... it's very nice. The floor is still COOL, because this is just intended to keep the floor warm - not heat the room, but I have friends that have the hot-water radiant heat (pipes thru the floor) and they have some of the most comfortable homes I have ever spent time in.

But - as someone else pointed out, where you live - to have AC, you would still have to have the ducts put in a for the cool air. I would definitely check out the radiant
heat - especially if you plan to have the concrete flooring - which can just "feel cold".

I like your other ideas. Is this a retirement home? Do you really want stairs if you plan to grow old in this house?

Can you separate the master bedroom/bathroom from the other bedrooms so that you have your "own space"?

Where you planning to put laundry facilities? They should be on the floor where the most bedrooms are - you don't want
to cart laundry up/down stairs. We put in a second laundry room in the basement where 4 teenager girls lived who ALWAYS
complained about "nothing clean to wear" - gave them their own washer/dryer and said "I don't want to hear about clean clothes
again" ...

Just some things to think about.