Read on Chowhound about Cooke's in Hyannis, 1120 Rte. 132, as a good basic fried seafood kind of place and was very pleased with reasonably priced scallop roll and fish and chips. They claim to have won many awards in 25 years in business and I am not surprised to read that based on a very nice meal. It is an order at the counter and the food is brought to the table spot, very informal, and plenty busy. Also in Mashpee. Spent less than $20.
A local shopowner in Chatham suggested the Impudent Oyster as a good lunch spot. The restaurant is off the main street, at 15 Chatham Bars Avenue, just behind the Mark, Fore and Strike store. It is a two level restaurant, quite light and bright on the top level, with a cosy, dark bar/restaurant area below. Scallop roll featured bacon and a mild cheese, and the French dip, although cold, was enlivened by a nice Boursin spread. Good French fries, cole slaw and red potato salad. Out the door for under $25.
Would happily revist both restaurants on another trip.