I've done it with and without dining plans and for the next trip, we're going without. I think the Basic dining plan is pretty good, especially if you like the peace of mind that comes with pre-paying for meals. I haven't tried the Deluxe plan, but think I could easily eat $72 in WDW each day, as long as I didn't eat everything on my plate. The Quick Service dining plan seemed great, but a review and comparison showed that it just doesn't fit with the way I travel and eat. Paying OOP is more flexible and I'd rather not feel like I have to have dessert with every meal or a snack every day just because I already paid for it.
alisonslp, with the way you described your family and your dining habits, I don't think I would recommend a dining plan unless you think you might do a counter service breakfast on a couple of mornings. If you did that, you could split your family's CS credits among lunches and breakfasts. But if you intend to eat all but the character breakfast in your room, you probably won't use all of your credits.