A couple of good places to start:
Winnebago Rialta Motor Home
Lots of good info on these sites.
big enough but not too big. At 22 feet, easy to drive and park
Great mileage. Average 18-22 MPG
Relatively good use of space
Low step in. Easy to get in and out of
Not ideal if you are over 5'10"
Not a lot of power ( either I5 or V6 )
Cannot carry a lot of weight. Ideal for 2+
There is a buyers checklist on the third site, please check it out