Summer Time is Seafood Time
Seafood is my favorite food. As such I've eaten a lot of seafood over the years and in a lot places. My favorite place EVER, is the Clam Box in Ipswich. It's the best, always fresh and I have never been disappointed by the quality or taste. Not just the fried stuff either, lobster roll, baked stuffed, etc.
Also if you time it right, you can get some great seafood and then head over to Cranes Beach (also in Ipswich) for an awesome picnic on the beach. Just perfect.
Here's a great link from the Boston Globe listing New England clam and lobster shacks.