A few threads recently have dealt with restaurants in Concord, and I thought it was worth collecting info on them into one Google-able post since I grew up there and still visit my parents there often. It's true that it's not a particularly inspiring destination for food but I thought I'd break it down. Please add your own thoughts, obviously this isn't an exhaustive list.
* Sushi House. Standard sushi menu but everything is very high-quality, and the ambience is nice.
* Chang An. This came up in another thread and I know not everyone likes this place, but it's my favorite destination for "Americanized" Chinese food, especially for the peking duck and moo shi anything.
* Papa Razzi -- same as all the others.
* Concord Tea Cakes -- really a bakery, but with a few deli-shelf meal offerings (sandwiches and pre-made salads, etc), lots of sit-down space, super-tasty and super-charming.
* Colonial Inn. Popular with tourists because it's housed in an old-fashioned, well, inn in the town center near all the historic sites. The food is hearty and decent but nothing too special, and fairly overpriced. Their brunch and special event menus tend to be good, though. The charm factor is high given the setting.
* Comella's -- they're all over the place and we have one too. Get your massive quantities of ordinary but good Italian food here!
* Walden Grill. Fine place to have a beer and watch the game, but the food is unimaginative and cafeteria-quality at best. I frankly am shocked they've been around so long. Servers are very nice, though.