We just picked up our Montana 3750FL last month and have camped in it twice. We plan on fulltiming with it. You know it's good when DW says she can see herself living in it the rest of her life.
The living room ceiling is plenty high, but not so high you have to get a ladder to adjust the AC vents. It got cool one night so we turned on the fireplace and closed off the living room and had to open windows it got so hot. I haven't figured out how to adjust it yet. I don't have the washer hook up directly over the kingpin so no added pin weight. DW and I cooked dinner one night and never bumped into each other. So plenty of room there. Big window at the back, so I can wake up to whatever scene I back up to. Really love the full width bathroom with the second door. DW has decided to turn that into a mud room when the dogs have been out.
Basically, it's lots of space, more inside storage than we know what to do with. Ok, so the basement isn't very big, but I honestly don't know what I will put in there besides tools and my grill. Overall, we love it.