One thing that we are firm on - one level living. I see you prefer that but are considering 2 stories. For us - at our age - we need a place we can 'age in place'... no stairs since it's likely that sometime in the next 15-20 years one of us will have mobility issues.
Do the places you are considering have a ground floor bedroom and full bath? Even if it's not the primary suite? Not having that option is a deal breaker for us.
We were firm on one level living also. DH even more so than I was.
But, we have both decided that under some circumstances this is not a dealbreaker.
First -- the stair width/shape must be such that we could put a good stairlift on it.
Second - the house, in return, must have everything else that is important to us.
Basically the stairlift solves our issues. DH doesn't like stairs because they have started to hurt his knees. He can walk on them but realizes at some point it may be difficult.
I don't like stairs because I am terrified of falling (I have fairly mild osteoporosis). I also have knee problems in one knee although going up one flight of stairs is really not an issue.
Initially when we rejected 2 story houses I just overlooked stairlifts. But -- I have a friend whose mother (mid-80s) lives with them and she has a stair lift. Basically she says it has been great. Works well (rarely needs maintenance or repairs) and solves all the safety issues. She also says it is great to use a lift to take packages upstairs.
I've done research on stairlifts and they can be custom made to fit most stairs (I will reject any house where it can't be done). They aren't all that expensive. My friend even recommends that we get one now even though we are both still able to use chairs. She suggests using them more for carrying stuff up and down stairs.
So - why not just get a house without stairs? They are very unlikely to be available with the amenities we want. Las Vegas has few 1 story houses and most are very small.
We want to have an at least 3 bedroom house where one extra bedroom is a guest room and the other is an office for DH or I. He and I both spend most of the day at our computer at our desk. We don't like being in the same room (we are each distracted by the other). So, the house needs to have a space for a 2nd house. It can be a 4th bedroom or a den or extra living area downstairs. But -- most houses don't have that. Most houses get that extra office space by having an upstairs loft.
We want to have a newer house. Layout is important to us as is just having a newer house. The average single story house I find in Las Vegas is about 10 years older (at least) than what we want. It usually has 3 bedroom (sometimes only 2) with no space for the second office (except us using the living room for it which is not ideal). Also, 1 bedroom houses tend to be smaller (often less than 1300 square feet). So I am very dissatisfied with most of the 1 story houses in the areas/price range we are interested in.
Having said that, there has a couple of times been a house on the market that is 1 story that checks all of our boxes. If one turns up when we are ready to buy, we would certainly go for it. But, if not, I think that getting a house that could have a stairlift chair would be acceptable from a safety and comfort standpoint. We absolutely would prioritize a 2 story house that had a secondary bedroom downstairs. However, that is also uncommon in Las Vegas.