Disposable sippy cups. If we were at a park and she drank milk out of it, I could just throw it away. I could fill one with water when we left the hotel and use it for milk later. If it only had water in it or we just used it in the room, I would wash it in the sink with some dish soap.
Disposable bibs. I like the Munchkin brand (Target) with the inside out pocket which catches everything (even at 2, she drops enough food in that pocket for a whole other meal).
I brought waaaayyy to many diapers. I would count for a week (or for whatever time you will be away) how many diapers you use and add 5 or 10.
Enjoy your trip!