We have kept our TT at 24' and resisted bigger options as long as we are traveling often. The smaller units are easier to deal with on the road, and you'll often find the better campsites with "smaller" TT's. We've been in a few very tight CG's in Wisconsin, that made our 24' look huge and out of place. The CG sites for larger units are often...wide open...dry...and boring.
When we travel less often and shorter distances, leaving it parked on our land "up north" most often, a larger TT will absolutely be in order. Until then, I love the high mobility, fully featured, low to mid 20 foot TT's out there.