It's not much, but I'm starting slow because I don't want a bunch of holes all over the inside of my new TT. And I'm trying to be thoughtful about what I modify (and I think pretty slow).
Anyway, for some reason, Coachmen left a big ol' hole over the refrigerator. So I installed a door that matches the doors over the sofa. To me, it gives a more finished look, helps keep stuff in while traveling, and my bride really likes it (bonus!).