I have a 20 foot TT. I, the girlfriend, and the dog have no problem in it. I have left the dog with my brother and taken a couple of kids with us. I've had up to 4 adults and one kid in it.
It depends, I suppose, on the type of camping you do. When we go out the Travel Trailer is just a place to sleep. We stay active all day outdoors. Then we set around the fire at night and then go to bed. When it rains we go to museums and other indoor things during the day. In those cases we would eat out and when we get back to the TT we can watch a movie and then go to bed. Rainy days are a little crowded. You have to have some rules and be able to get along on those rare occasions.