Having just come back from a business trip, I tried something different. I would usually just chuck the diet out when I traveled.
This time, I said no to desserts, even if everyone else was having it. I have a friend who is super skinny at work, and I was watching her eat, and I following her lead. She didn't eat bread that was served in the restaurants, she ate a ton of fruit and salads, she always asked for the sauces on the side, she drank only water, etc.
I'm on that kick right now -- to watch how skinny people eat. It's been enlightening.
Bring snacks with you, there will be grocery stores, buy snacks there, and take them with you -- it's cheaper than buying a snack on the street.