We all tend to use travel as an excuse to overeat, so doing some calorie-burning time early in the morning or before you go to dinner helps you avoid those extra pounds, too. But you have to have a plan. It won't just happen. They're easier to find than ever. Some hotel gyms are pretty crummy.
Some hotels charge extra.
If a pool is important to you, ask about that, too. Jump ropes are light and portable and you can't beat them for working up a healthy sweat in just a few minutes. Another highly portable, highly recommended piece of gear is an exercise band or tube. Either hire a personal trainer for an hour to give you a routine to travel with, or check out one of the many Road Workout fitness books. It is simple to turn your hotel room into a perfectly respectable workout space, using a chair, a towel, the bed, etc.