Definitely eat breakfast at Chick and Ruth's, it's a diner on Main St. If you go on Friday you might not have to wait in line, but if you do, it's worth it just for the local color. For dinner you can take the water taxi which leaves from the docks and go to the Chart House or one of the other restaurants over there. Reservations are suggested at most restaurants - look on Google maps and the restaurants are shown.
There is more shopping than anything else, but maybe the State House gives tours, we didn't check that out.
Are you there for the entire time he's at NASS? I don't know where your from, but if you've not seen the beaches on the east coast, head to Rehoboth Beach. You could also venture to Colonial Williamsburg if you want an overnight away from Annapolis - it's very unique. My kids thought it was too contrived even when they were in 7th grade, but it's interesting.
There's some crab place everyone talks about, but I haven't gotten that far in life just yet - someone want to pipe in on that?
Have a nice vacation while your son is dragging big logs around in the Severn!