I have been on Weight Watchers for 6 months, but I am going to relax my stance a bit on my food and wine festival trip.
But a month after I joined WW, I had the Adventures by Disney trip to California. Most of the inclusive meals were buffets. The other meals, I used my best judgment to keep to smaller portions than what I was served. Here's what I did:
Buffets:
Walk the perimeter of the buffet and check out all items before picking up a plate. Don't skip the "bad" stuff if you really want it, but take a small portion of it. And if you make return trips to the buffet, choose veggies or fruits, aka the "filling foods".
Counter Service:
There's usually a healthier option than burgers or hot dogs, so I tend to choose those things. Instead of fries, ask for their healthy option, which is usually a pack of baby carrots or apple slices.
Snacks:
All the parks have fruit and veggie stands. Find them. I like to hit the stand near the Kilimanjaro Safari at AK.
Full Service:
Before you order, check out the menu. Avoid breaded or fried foods, if possible. And when you get the meal, look at the portion. Most often, you're served double what we're supposed to eat. While the little girl in me who was a member of the Clean Plate Club hates to leave food, I had to condition myself to think it's ok to do so. When you order something like a mac and cheese entree (which I did at the Uva Cafe in DLR's Downtown Disney), I ate half and was satisfied. I didn't deprive myself if I wanted something that wasn't entirely "healthy".
And when you want to indulge...go for it. But also look for opportunities to get more activity in. Walk another lap around World Showcase Lagoon.
The important thing is that you're still having fun. I'm definitely going to do a lot of splurging during my October trip, but I know that I'll get back on track when my trip is over.