I have to say when I went from a trailer (Small. bumper pull type) to a class A, it was indeed "BIG" and I mean BIG!!!!... (Well the trailer was a 13 foot scamp. Fully set up this 37'7" class A is 13 feet WIDE) so it really is BIG.
Even my brother, a professional OTR Semi driver used to hauling 160,000 pounds (Flat steel) says when he drove a class A it was BIG,, In fact it is, six inches wider than his semi.. Only other vehicle allowed on Freeways that wide without permits are Flat Bed Tow trucks and construction machines used to build the freeway (And those need permits outside the construction area).
So it is big.. Took me two trips to get used to it,, Then it was as natural as driving the lumina it towed (1992 Lumina APV,, AKA Dustbuster).
Advantages: class A: You are sitting (usually) higher, on a level with many Semi Drivers. Gives you the ability to see what's ahead of you several cars ahead (Major safety advantage)
On a long trip, from time to time I need to pull over and go somewhere.. I can pull over most anywhere wide enough (Though I prefer to "Rest" in rest areas) and if it's pouring down rain out.. Go where I need to go and not get soaked... Or if there is no rest area any handy parking spot.. and My rest area is INSIDE no need to play in traffic. (Trust me that is a MAJOR advantage)
Driver's and passanger's seats swivel to become House seats.
I mentioned it's BIG.. Inside and out.
Finally.. Millage: Now be it a 37' Class A or a 37' 5th wheel with sufficent tow vehicle... aboutr 8-10 MPG is what you can expect
BUT: I get to the campground and want to go to church, or to the store for food, or to the "Attraction" (Whatever the attraction is) That truck gets generally less than 20 MPG bobtail (without trailer) in fact 15 is often closer.. My New towed (Dodge neon) Gets 25, and modern toweds (mine is a 2001) often do 30-40 MPG. And I drive at least as many miles with the NEON
Oh, one other advantage.. For a time we did not have a towed.. We drive the MOtor home everywhere.. It's July/August.. Temps otside in teh 100 range (Actualy high last week here) I come out of the store with the ICE cream and put it in the freezer BEFORE it melts (I have an aux freezer).
Now I do have a cheat with the car (Picnic cooler with ice packs in it) but nothing beats putting it right straight into the freezer.
Oh, additional advantage.. Spare vehicle.. Yup, if My motor home "Goes flat" (Blows an engine) and I'm out of cell range (I was not) Drop the towed and drive to a place I can summon help... Or if the car dies (it did) I can run to the store in the Class A (expensive but doable). Which I did. for like 2 years.
Am I glad I upgraded to an A: For sure. No regrets. NONE, zip, Nice ride.
Mine is a gasser.. but man does it ride nice.