random thoughts.....individual thoughts of others may vary.
The placement and the number of electrical plugs....are there enough and are they placed in areas that fit your needs.....Around kitchen, in the sleeping area, in the area you might want to use for electronic or as a desk. Outside?
placement of TV
Low Point Drains and switches for the bypass on the water heater...useful for winterizing, etc.?
What can you still use with the slide/s in? Some slides cover part of the kitchen access. Some make getting into or out of bed much more difficult. When it gets real windy and or cold many of us pull slides in to help hold the heat in or to prevent damage to slide toppers.
Is the storage useful for the sort of stuff you haul around. XXX cubic feet of storage may mean several small spots none of which will hold a camp chair (or and inflatable kayak)
Xtra large storage areas may look nice but, one, they may be difficult to keep organized because they are so large. Two, you may be more limited than you think regarding how much or what you can store in the extra large area because of the need to balance weight across both axles, etc.
My second rig had the exhaust pipe coming off the back of the rig. I had to pay to have its placement modified so that it came off the side otherwise it would have melted anything I tried to haul in a rack off the back off the rig. I discovered this after damaging a nice outdoor rug....
Does it have enough counter space in the kitchen for you?
My initial Class C had the Ford engine. It was very hard for me to move into and out of the drivers seat from inside the rig. My feet are large and I was always tweaking my knees particularly as I was getting out.
How easy is it to fill the rig tank with fresh water? Is it easy to switch from using campground water one stop and use water from the tank the next night?
Are you able to close the bathroom door and still move? In my small 22 ft unit, I didn't worry about it, I was just so happy to have the bathroom and small shower/tub. But what is large enough for a petite Liz might not accommodate me and my elbows.
When you get a chance to visit folks, any of us or other RV folks you might know, don't hesitate to ask for a tour of their rig. As important as it is to walk into outfits sitting at the shows or on lots, observing how individuals modify or organized their space may give you insight in how you might live in a small space yourself.