I could write you a book
Just did the same thing this time last year. First, go by the Herrshoff (sp?) Museum up the coast from Newport,still on the bay. Across the street from there is there is the America's Cup Hall of Fame museum and see the real Stars and Stripes (new cup class class, not 12m). Also see Intrepid, and other classical wood boats. Great visit.In Newport, take a charter on a 12 meter, maybe even take the helm, I did. Sail on the replica of the first America's cup boat "America".Visit Newport Yacht Club, and New York Yacht Club.You can charter a few smaller boats too for a day sail.Not to mention eating lobster, visiting Newport's mansions, walking on the waterfront, or the cliff walk along the shore side of the mansions. Plenty of shopping, cool nautical things. The large boat yard was really cool to see very large yachts in and out of the water. They will let you do a little sight seeing there too.Overall there is plenty to see and do, just look around. This may not be really geared to kids, but Newport is really all about sailing and its history.