I agree with what AnnieT said!
We spent a week at WDW in March, and I also came back lighter (despite eating all over the World!) I'm also a Weight Watcher.
My strategy was similar to AnnieT's. I would start the day with a small breakfast. Maybe Cheerios and a banana and nonfat milk, or an English muffin, or yogurt... I tried to start the day the same way I would at home.
For lunch and dinner, I would simply try to make the best available choices at wherever we were eating. This meant avoiding fried stuff or creamy sauces, and trying to substitute salads or veggies for other things at mealtime. There were several occasions when I had a burger and fries.

I did not count points, and I did not pass up desserts!!!
My philosophy was that this was a vacation I was going to enjoy, and my goal was to maintain my weight that week. I would not have been too upset to have a very small gain that week, but I think all the walking made the difference.
My advice is to enjoy your vacation, make common-sense choices, and don't fret too much about the points while you're there!