shoes are the biggest problem. i dont like to wear running shoes with EVERYTHING (no offense to those who do it) so i find packing multiple pairs to be the biggest problem.
not sure if most carriers have gone to this or not, but since most pubs are electronic now, that frees up a lot of space in a flight case if you still choose to carry one. I can end up packing light jackets and extra pairs of shoes in a little divider, and my headset and flashlight etc on the other side. even has room for a small laptop