Talk about good timing. This week Legal Sea Foods took the top spot in a national, month-long USA Today survey asking readers to choose their favorite seafood restaurant; Boston was also represented by Union Oyster House (#7), the oldest continuously operating restaurant in the country. (You can find the full list here.) And last night (ta-da!) Legal opened its new Legal C Bar, part of a small contingent of contemporary, cocktail-centric restaurants serving clams, calamari and more for noshing. The Lynnfield spot is the latest in a number of elevated chains to set up shop in the open-air development MarketStreet: Davio's, also locally rooted, opened doors there last month, Wagamama (a British-born global chain that only has a U.S. presence in Boston) opens October 21st, and Brookline sushi favorite Fugakyu is slated to add a location there next year. The Legal C Bar opening not only rides the wave of its accolades, but has (thank heavens!) happened in time for Saturday: deemed yesterday by Governor Deval Patrick to be "Lobster Day in Massachusetts." Health care, debt ceilings: maybe Capitol Hill would be more productive if it started tackling food holidays?