Take the Samuel Adams brewery tour in Jamaica Plains:

http://gonewengland.about.com/cs/bos.../aa080300a.htm

JP

Swan boats don't open until April 19, but are cheap, relaxing, enjoyable tradition in Boston. I suggest the Freedom Trail, of course, guided by one of the costumed historical characters, starting at the Commons. Then take a Duck Tour (our guide was hysterical) - some overlap with the Freedom Trail, but not that much. Then get a Fenway tour, or take in a game if there is one available.

I'd recommend forgetting about a car if staying at the Parker House or anywhere downtown. We paid $28/day parking for 5 days at our hotel and didn't take the car out once - rode the T everywhere (we had no choice, the car was part of a longer New England trip).

We enjoyed the New England Aquarium - it's small but well laid out and has some great exhibits. The wife is crazy about penguins, and she fell in love with the little blue ones (they have 3 kinds). They also have the world's only trained sea turtle.

The following are all great 1/2 day easy walking tours:

North End - dozens of Italian restaurants & shops, plus Paul Revere's home and the North Church.

Back Bay - swanky shopping on Newbury St., Copley Square, the Library, Prudential Center (& the observation deck).

Beacon Hill - stroll by rich brownstones, the State House, the Black History trail, John Kerry's house, the bar from Cheers.

Harvard Square - shopping, food, see the glass flowers exhibit at Harvard, cool bookstores.

South End - very nice residential neighborhood with tons of nice restaurants, theaters & shops mixed in.

Also, from Parker House it's only a few blocks to Fanueil Hall (history, shopping, food that ranges from very cheap to expensive). If you have a chance, take in Blue Man Group - their theater is only a few minutes walk, and there is a 1/2 price, same-day ticket booth at Fanueil Hall (also Prudential Center).