A worthy alternative to the great fried clam shacks of Massachusetts’ North Shore, Agawam is a ship-shape, pint-size diner that is all silver sunbursts, pink laminate paneling, and red-upholstered booths. The menu is pure and traditional diner fare, including beef stew, hot hamburger plates, luscious grilled cheese sandwiches for less than the cost of a junk-food hamburger, and breakfast that is virtually instantaneous.