Let me preface this by saying I have a 28 ft (29'5" bumper to bumper) class A with no slides (2002 Safari Trek 2830) and so far we are traveling without a TOAD. The longest trip I have made in our coach is just over a month, with my wife along for the middle 2 weeks of that 4200 mile trip. It was overall functional for 2 people, though the Trek is a somewhat unique layout as there is no bedroom, just a mechanical queen size bed that lifts into the living room ceiling, the byproduct of which is a very large kitchen and bathroom (nearly 7 ft of kitchen counter top space, and a 5x6 ft bathroom. Slides would of course primarily add floor space, which can be nice, but they also tend to limit movement around the coach when the slides are in.
My overall impression living in this amount of space was, it was fine for limited time together, though if it would extend more than 2-3 weeks a separate bedroom would have been nice, just for the occasional privacy separation. Things were much more comfortable for the solo portion of the trip, though after a month in this limited amount of space I was glad to get back to my sticks and bricks house, I suspect I would feel similarly in most RV living situations. There are limitations in cargo space in a coach in this size range, though there is room to carry all of the important stuff, plus many of the luxuries most people like to have along (BBQ grill, canopy tent, camping chairs, etc.). To give you an idea of the basement space limitations, I have given thought to adding a portable fire pit, though honestly I am not sure where I would store it, there is space, but it might mean moving some stuff to the drivers side cargo bay. The big thing that will be lacking in almost all sub 30 ft coaches will be no washing machine or dryer. The other issue we run into is not so much lack of room for cargo, but bumping up against our cargo carrying capacity weight limit, if traveling with water in our tanks.