We have a couple of quotes to instal conventional ac.

We have a raised (not split level) ranch
Enter on ground floor/slab w no basement
Full set of stairs to main living space w kitchen , DR , LR and hallway to 3 bedrooms (typical ranch layout)

Ceilings in mains areas are vaulted

We have a gas forced hot water for heat

Planning to cool main floor only (2nd floor) because usually cool on ground floor in summer.

1500 square feet to cool
Unit in attic accessed by hallway to bedrooms

My main question is on the number of return vents.

One contactor says we only need one located in the hallway and that would be sufficient to pull warm air even if the bedroom doors are closed as long as there is a 1/4 in gap. (I.e if you can "stick your finger undr the door")

Contractor 2 said absolutely need return in each room for max comfort and that it would be much more quiet.

Thoughts on noise level?
Comfort factor with single vs multiple vents?
Will the vaulted areas be as cool as the bedrooms ? My fear is that if we set to cool main area, in order to get cool enough the bedrooms will be freezing. It will only be a single zone.

Am also working through our construction contractor with one quote
(Not in writing). Vs a larger company popular on Angies list.

My stomach is in knots over this. Don't know who to believe and it is a lot of $$$

Thank you for any advice!

Ps live in natick massachusetts