I love Newport! Peter, we stayed at the same hotel for our anniversary 10 years ago, and I don't recall its name, either. (Of course, it might have changed since then.) We've been back a few times since, including a couple of day trips as well as cruise ship ports of call.
Back in Boston, the Freedom Trail and USS Constitution are must-sees if you're into American history (or just want to learn more). As it's part of the Park Service, the Freedom Trail is (pardon the unintentional pun, free), although there are admission charges to some of the attractions along the way. The North End is a favorite neighborhood. Janfred, most of the restaurants are along, or just off of, Hanover Street. There are so many to recommend. General rule is to walk by, take in the aroma, and if you see lots of diners inside, go for it! No matter what, stop into Mike's Pastry on Hanover Street. I usually don't eat sweets, yet I make an exception here.