The “20 Feet” refers to the number of human and canine “paws” in chef Marc Cassel’s household, but you’ll want to focus on the part that says “seafood joint.” We were tempted greatly by the classic Green Room mussels, but we could not resist the chilled tomato-champagne (vinegar) gazpacho, a refreshing purée afloat with croutons and diced tomatoes, onions, and cucumbers. And of course we had to get the pricey lobster roll, its toasted bun stuffed with big hunks of lobster (bathed in a sauce that could have been a wee bit perkier). (6/13)