The only problem I see with P90x is that it doesn't do much for the times when you're not working out. Otherwise, it seems to work great.
Personally, I use Advocare products (works for Brew Brees and many others) and have lost about 20 lbs and only work out occasionally (right now). The key is that the supplements help control my cravings and work throughout the day to give my body the nutrition it needs and doesn't get from the foods available today (it is proven that even fresh foods are providing fewer and fewer nutrients due to the changes in farming techniques and genetic changes)
The key to either system is to work very hard at having it become your routine. That means that while you're in your hotel, force yourself to hit the workout room before you go to bed or before you leave in the morning.
Force yourself to eat smaller meals more often throughout the day (4-5 total) about 2-3 hours apart and you'll see that your body will respond by speeding up your metabolism and dropping weight.
Good luck, I'm getting married next year, so I'm starting to ride my bike to work everyday and workout on the weekends. Forgot how much I can enjoy riding to/from work.