For me, any 2-credit restaurant that doesn't cost at least twice what a 1-credit restaurant would isn't worth the dining credits (which means, NONE of them are worth 2 credits).
To do a really rudimentary calculation, let's try and figure out the approximate "dollar value" of a table service credit. The DDP (2014 pricing, I think) is $59 a day for an adult. Assume you're buying lunch at Columbia Harbor House (entree, drink and dessert cost about $18 altogether) and having a Dole Whip ($5) as your snack. That means that in order to break even with the out-of-pocket costs for the same items, your table service entree/dessert/beverage combination needs to be worth at least $36. (Of course, if you ate a less expensive counter service meal or didn't use all your snack credits, you'd have to work even harder to break even.)
So assuming that each table service credit is worth $36 or more, two of them are worth at least $72. Thus, unless you are going somewhere for dinner that will cost you at least that much (and I cannot think of a single meal that has that steep a pricetag -- I'm sure you could get that total somewhere, but you'd be straining to order the most expensive options instead of what you necessarily watned to eat), you're getting less than full value for your dining plan credits if you go to a 2-credit meal.
We like to try "2-credit" experiences on every trip, but if we're on the dining plan, we never use it for them: we pay out of pocket instead and "spend" our dining credits on 1-credit meals instead. Better yet, we forego the dining plan and spread our dining between restaurants that offer great value, and multiple signature (2-credit) experiences.