If you have or are at the age where you start having knee problems, you will be better off with around a 27 foot class C with rear bedroom and RV queen bed. Climbing down and back up a ladder in the middle of the night will wake you up more than simply getting out of bed and going to the john. The overhead bed is good for storage and/or entertainment center. A 27 footer will have more rear cargo and cabinet storage areas than a 21-24 foot floor plan. Sleeping on a jackknife couch or convertible dinette cushions gets old quickly. A 27 footer can usually be parked reasonably near restaurants, tourist attractions and malls. You probably don't "need" slides. Equipping for boondocking and cold weather comfort are more complex matters.