It is probably easier for me in some ways because I live in Scotland, but I always buy a whole lot of souvenirs to take with: the kind of stuff you get at the tourist places like tea towels, key chains, scottish shortbread and anything else that looks really lovely (IMO). I always have 2-3 things in my backpack and when someone does something outstanding, as often happens, they get a little gift.
Sometimes it is nice to have them to give to someone who has unjustly taken the brunt of another guest's rant. Like at our foodcourt last year the poor CM at the cash register was being yelled at by a guest in front of us and all because they were having a bad day and she was just .... there. It seemed appropriate once we had paid to slip something onto the counter and tell her that she is appreciated and deserves a magical day from this point on - then leave before she could say anything.
I am sure that everyone could find something from their state that is a bit different. Or a card even would be a nice touch.