I am also from the Boston area (MrsBart, are you northshore too?) I would double-reccommend the following:
The Acquarium, Cambridge (Boston and Cambridge are 'walking cities' - so lots to do and see and SHOP), Any of the museums (Contemporary one has received rave reviews recently, and I always love the Museum of Fine Arts), The North End for italian food, but Charlestown for some other really good restaurants (there's one street with 4-5 really good ones, but I cant remember the name of it!! sorry!!).
For nightlife clubs, you may want to go downtown to Lansdowne street, there's a ton of clubs on that street (some are shady, some are ok, I dont frequent it, and when I do go, I am almost always with a group of males anyway), and Jillians is on the end of the street (atomic bowling/pool/sports and tv bar).
There's also a ton of bars in Fanuiel Hall, mostly touristy bars, some ethnic (think Irish), but bars nonetheless (some are pretty good), and during the day, this is a tourist hotspot too.
We are definitely a sporty city, so seing the bruins or the celtics or even visiting fenway park is a MUST
when you are here, if only for the historic significance.
OOOH, Restaurant week!!! I LOVE this week in Boston (there's one in the summer too!), You picked a GREAT Week to come to town!! For $20.07 you can get some REALLY good meals, there's always write ups in the local papers about the best places to go too (Boston Globe)!!
Definitely use the T for transportation, dont bother renting a car unless you stay far out of the city. Even then be prepared to drive in, park somewhere, and pick the up the car at the end of the day to drive out (yes, traffic is horrible, and yes, the roads do change DAILY-that wasnt an exaggeration), or unless you plan to visit other areas of this or other NE States.
Newbury Street is the local 5th avenue, and has lots of cafes and high-end shops, and just parallel to that is Boylston Street, and the Prudential Center (mall - "the Pru") - also a high tourist area. At one end of Newbury is the Boston Common and the Public Garden (not to be confused with 'the Garden' aka the Fleetcenter, aka TDBankNorth Garden, where the Celts and Bruins play). These two areas are about the most amount of green you will see in our lovely city.
I cant really help on hotels, as I dont often stay in hotels in this area, but probably you will appreciate staying as close to the center of town, even if it is a little more expensive.
I dont want to sound like a Mom here, but seriously, we are known for our bitter weather, even in march. Layers work best, (ears and hands covered) and definitely check the weather before you come, it's been kinda crazy lately.
I hope you have a wonderful time here!