we did the dining plan in June with our family (me, dh and ds#1..ds#2 was under 3) and really enjoyed it as well.
I have also been on WW for just over a year (lost 35 lbs) and while at WDW, tried to make intelligent choices for my foods. I shared when possible, only ate 1/2 if sharing wasn't a choice (like the wrap at Pecos Bill's) and tried to stay away from the really heavy, creamy sauces. Also didn't eat a lot of ice cream, although it was as hot as sin while we were there.
With all the walking, I didn't gain at all during the trip. Which I think is a great accomplishment. Hope you continue to enjoy your trip.
We are also new DVC members (taking our first trip home Nov. 06) and I'm hoping by then, they will have some way to offer the dining plan to us. My kids are not easy breakfast eaters (if only they liked a bowl of cereal!) so eating bkfst in the villa is ideal for us, but they like a good lunch and dinner (at least the older one does). So CS and TS are good for us.
Looking forward to your continued report.