depends - are you planning on dinners instead of breakfasts? and do you ahve kids in your group?
I think the dining plan is good, based on the buffets we have scheduled. It also can be a better deal if you have kids, because of the pooled credits.
dinner at 1900 Park Fare is $28/adults and $13/kids
2A2C is $82 plus tax ($5) and tip ($15) = $102
and you still ahve the counter service and snack credits to use.
dining plan cost for 2A2C is $98 plus tax, so in this case, the dining plan is a deal. basically the counter service meals and snacks are free.
At Boma for dinner
$25/adult $11/kids
the dining plan is $11 for kids, and includes the gratuity for the TS, plus a counter service and snack, so this is a good deal.
$25 adult plus tax $1.50 plus tip $4.50 = $31
if your counter service meal and snack total over $6 (and they probably will) you come out ahead, how much depends on what counter service meal you get.