I seem to "road trip" alot, so I had to start thinking ahead to keep my fitness on track! Whenever making hotel reservations, a good fitness room or pool is a priority for me. Even if the pool isn't big enough for laps, I can do exercises from my water aerobics classes for a good workout.
If neither of those is an option, I always carry an exercise band w/ me so I can do an impromptu strength/stretch workout in my room. And if you can take your laptop w/ you, don't forget about Sparkpeople workout videos... they are always available. Traveling is never an excuse to skip workouts!