Hello from AZ

[Tom in PA]

Welcome to our RV family... your new home on wheels.
Some advice here from a veteran, both military and RV. As others have said, decide how you will use your rig; A week or two at a time...or four months snowbirding. This is where space is a consideration. 40-45' with four slideouts should give any couple enough private space to make living aboard in a new place enjoyable for months.
Short trips? Get something smaller.
The important part: Buying an RV is not the same as buying a car and there are no guarantees that everything that isn't working when you take delivery will get fixed immediately...generally not. I could write a book on the buying process and the internet is flush with agonizing stories of broken promises...a great many having to do with Camping World.
Buying a brand new motorhome is not a good idea financially or if you plan to actually use it. There will be many items that aren't working that the manufacturer expects the dealer to fix. That usually doesn't happen until the coach is sold to you and then on your fist trip you discover the problems. Your coach goes back to the dealer where it can wait weeks or longer "for parts."
It has been my experience that a two-to-six year-old, clean used RV would be a better experiene because the original owner suffered the enormous depreciation and fixed all the problems. Golden years for a Diesel coach might be 30,000-60,000 miles on the speedometer. The Diesel engine and drive train together are good for 250,000 miles or better with proper care.
All of this is based on Class A motorhomes. Trailers and 5th wheels are very popular right now and you'll need a good truck to pull one. Driving these rigs can be more challenging than a conventional motorhome and backing into a camp site is late afternoon entertainment in RV parks. They are not designed for really cold weather usage.
Recommendations? Tiffin owners love the support they get from the home base in Red Bay, Alabama.
Late model American Eagle coaches hae a lot of bang for the buck and are well-built. One bug that I see lurking in American Coach is the very long slidewall that is moved in and out by four electric motors, synchronized by a small computer. That wall is about 80% of the length of the entire coach. It would be difficult to retract that slidewall under emergency conditions without a lot of help. In fairness, I've never heard of one failing.
If you've got the bucks and want to go large, a converted 45' Prevost bus is the most ruggedly-built coach you'll find anywhere. Service is available almost anywhere in the US & Canada.
Older Class A's from Monaco, Tiffin, Newmar, Travel Supreme and, to some degree Sportcoach can be good deals on generally reliable rigs. I'd avoid Entergra.
All of the above coaches are Diesel powered. The ideal would be a pre-DEF coach with lower mileage (under 70,000).
There will be many who will disagree with me... this note is only an opinion. So do your reseach!
Final advice on fixing things: Follow the ground!