Christy,
I think the Quick Service Dining Plan is a nice alternative for people who do not like to plan far in advance. The Basic and Deluxe Plans include table service meals, which require making reservations in advance (the earlier the better, sometimes 180 days in advance!)
As far as actual value, I'm honestly not sure that you're saving much (if any) money by using the quick service plan. I'd look at it more as a way of locking in prices so your budget has a fixed expense. The reason I say that is because current pricing (8/08) looks like it will be $29.99/adult, $8.99/child, plus tax. For a child that is probably a money saver (kids meals are usually $4.49 each, and you'll also get 2 snacks per day on this plan). For an adult, it can go either way. Counter service lunch prices range from $6-$14. We usually guesstimate $10 for an adult quick meal. You do get dessert on this plan, also. If you like dessert that's great, but since we wouln't typically order a dessert it doesn't hold much value for me. Desserts would add another $2-5 dollars to that price, so now maybe $13 per meal. Add to that the two snacks per day (generally anything under $4 counts as a snack) and you're getting close to the plan cost. What type of snack you choose will affect the value also - soda is $2, but some snacks are closer to $5.
What all of that boils down to, for me, is that it's valuable for convenience, but not for money savings. I wouldn't normally buy dessert, so I don't see that as a big perk. If I bought my typical counter service meal and bottled water for snacks, I'd come out ahead by paying out-of-pocket (my cost then would be more like $24). Again I want to emphasize that this is just how I look at it; for your family it might be a great thing. For my family, we'll stick with the basic or deluxe plans.