We fulltime in a 33C (34'). Because we love the floor plan and the space, we see no need to go larger. We've stayed in quite a few campgrounds where a larger rig could be prohibitive - either the size of the sites or the number of larger sites available. As for storage, we still have empty space but are actively trying to shed weight for more batteries. The only thing a larger coach might provide for us is a greater cargo capacity. We don't need a second bathroom or another chair/couch.
I think a lot depends on how you live before you RV. We had a 1500 SF house but only lived in less than a 1/3 of it. We also don't have a need for 'stuff' so the rig doesn't get crowded. If we don't have a space for something, either it goes or something else goes so we do have space.