Congrats on joining WW - I've been on plan for about two years now and have lost 70 lbs, so I definitely understand wanting to stay on target while on vacation!
I've been to the World twice while on WW. The first time, May of 2010, I lost 3 lbs - probably because we were hiking up to 7 miles a day in 90+ degree heat! The second time, Dec of 2010, I gained 3 lbs - probably because we stayed inside most of the time because it was in the 30s!
Honestly, I went into both vacations just thinking I would be "smart" about what I ordered. I typically ordered grilled fish or chicken as I didn't know how lean the beef would be. I also asked for most things to be prepared without sauce, or to bring sauce on the side (easy for me as I like most things plain anyway). Forgot to mention, we were also on DELUXE dining (ate 3 table service meals a day)...I usually had a salad for my appetizer and always had dessert! At places like the Plaza, most sandwiches come with fries, I would get whatever the other option was, so I didn't even tempt myself with things I didn't need!
Good luck to you, it definitely can be done!
Edited to add: GOOD POINT on fruit being a 0 points plus value now! The great thing about Disney being in FL? Always lots of fresh fruit!