I pack instant oatmeal as well and make it in the hotel in the morning with the coffee. No microwave? - just use the coffee maker to heat up some water (the single serving ones are the best for this). I find if I start my day with something filling, it helps stave off getting hungry when you land back at base. Peanut butter sandwich on whole grain bread as a mid day meal. Then depending on the trip, I'll try to get one healthy as possible airport meal (Subway but I also try to not overdo subway) that I can have half of then, then the other half when I get to the hotel.

It's actually important to have several small to medium meals a day instead of 2 large meals. Helps keep your metabolism up. Also a good workout routine. I am a big fan of P90x. I cant always bring it on the road with me but there are certain P90x workouts I can do in the hotel room that are good cardio, especially after sitting for 8 hours. Yoga and Kenpo can be done without disturbing the people below you.