I'd recommend the W Boston. In terms of walking, the hotels are equidistant from Quincy Market (Faneuil Hall area) but there is a lot more to see along the way if you are going from the W.

The hotel can point you to the Boston Common (no -S), the oldest public park in the United States. You can walk along Tremont Street on the same side of the street as the Common. You'll pass the Granary Burying Ground, currently home to some of Boston's most famous dead people, after which you'll come to the intersection of Tremont and State. Take a right on State (If you kept going on Tremont, which turns into Cambridge, you'd eventually reach the Liberty Hotel area), keeping Government Center on your left. You'll cross over Washington Street and see an old building, more commonly known as the Old State House. See all those people gathered around that circular thing in the ground? That's the Boston Massacre Site.

Cross diagonally, over State and Congress. You'll know you're in the right spot if you end up at the Bank of America branch, which is currently under construction. Walk down Congress Street about 100 yards and Fanueil Hall/Quincy Market will be on your right. That's the site of the second Boston Massacre, which is how it will feel to you if you pay the exorbitant prices to eat the lousy food in the food hall/marketplace/whatever they're calling it these days. Still, if this is your first experience here, bite the bullet and buy something there.

If you don't feel like walking back to the hotel, you can catch the Green Line T inbound to Boylston Street, which puts you back right by the W.

Mike