Essentially, you have the same situation as anyone else asking "are any of the dining plans right for me and my family?" You may have already convinced yourself of the answer, but you are in the position of trying to get someone to agree with you.
The answer to the question has multiple factors, though. One is the cost issue -- will going with a specific dining plan save you money? Generally, if one of the plans matches the way you would normally choose to eat out-of-pocket, then you're probably going save money on that plan.
In many cases, though, going with a dining plan can cost more than paying out-of-pocket. When having to deal with things check by check, people may choose to economize by having fewer meals or choosing lower-end options. Going with a dining plan, even if it winds up costing more, can have a positive impact on the overall vacation experience due to the freedom from having to "penny pinch" on vacation, allowing people to order whatever they like instead of just the cheaper or "safer" options.
On the other hand, all of the plans (except QSDP) require planning. You have to have a solid plan that makes use of all of your credits, or it's going to be a bad deal financially. This may result in a higher degree of commitment than some people would like; when paying out-of-pocket, with few exceptions, you can cancel last-minute with no repercussions if you simply don't feel like a big meal at that time. On a dining plan, you now have extra credits that you will have to find a use for, which may not always be easy except in very off-peak times.