My very best laundry situation was in a vacation rental home in Palm Springs - house was a rancher and the laundry was in the hallway en-route to the bedrooms. Not right next to the bedrooms, but still very close and it was well equipped with a nice counter for folding things and places to hang stuff up that needed to be hung up right away.
Our last house? A split level, with basement - laundry was in the basement, but I didn't mind it - because the laundry room was super bright (husband put in very white flourescent lighting in there). I still had to carry laundry up three 'half-flights' of stairs but it was ok, because the laundry room itself was so functional (tall floor- to-ceiling cabinets for cleaning products, garment racks, tons of hangers in a giant basket and a folding table).
Right now? I'm in a very old Victorian - laundry is in the basement - lighting is terrible, no place to fold anything, the stairs are extremely narrow and very steep. I pretty much hate it. It's dark, creepy and ugly. There are spiders down there. There's a bare lightbulb hanging from a socket in the ceiling. Every time I go down there, I swear - I hear "scary movie music."
...
I guess I'm saying it depends on the house? And it also depends on how well equipped the laundry room is going to be. Ideally, I would suggest a functional laundry room (not just washer and dryer in closet) as close to the bedrooms as possible. It's easy to bring up tea towels and washcloths from the kitchen.... but it's a royal pain to carry clothes to the main level or basement. Dream situation would be an actual laundry "room" close to where most of the bedrooms are. Not a closet, but a room that has super bright lighting, a place to fold, a place to hang stuff etc. Nice cupboards for storing various detergents and stain removers etc.
If it's not possible to have an actual laundry room on the floor where most of the bedrooms are, I'd still vote for basement - but it *has to be* super bright, has to have nice cupboards for cleaning products, a garment rack and/or giant closet rod etc. In my old house, I'd hang up all the stuff that needed hanging, toss foldable stuff in the basket and go up the three half-flights of stairs - dump the laundry onto a clean bed and fold it up there. Also kept my ironing board on a hook in my closet and the iron on the top shelf of the bedroom closet. I didn't mind this routine, because my bedroom had really high ceilings, a giant window with a beautiful view, and it was actually kind of nice to iron and fold in there.
Current house - basement laundry area is dark, there are spiders, there's no place to fold things, no place to store laundry cleaning products.
In the end, wherever the laundry 'room' is - it needs to be very bright, clean, functional and pleasant to be in.
I would not put a laundry on the main level if the bedrooms weren't there - I'd keep it in the basement and make it as nice as possible. So, in my view - it's either basement or on the floor where all the bedrooms are.