Sugar and Sun, depending on where you live, the Vermont City Marathon (usually run the Sunday of Memorial Day Weekend) is a great one. It's a nice size (not too big, not too small), in a beautiful location (in Burlington, VT and run on the shoreline of Lake Champlain), well supported, and has a great vibe. That was my first marathon and I was quite happy to do that one. Also the course is sort of a clover-leaf setup so spectators can stay in more or less the same spot and you'll pass them several times. That was great for my dh.