You MUST catch a game at Fenway!! OH SO worth the money!! Get to game early early and enjoy an empty park! Also, on non-game days you can take a Fenway Tour. DO IT! Fenway is so neat: for the Red Sox fan, baseball fan or history fan. :)
I have been there twice and have stayed at two different sides of the city.
I first stayed at Omni Parker House in the financial district. It is super pricey and the reason we stayed there was because we got a really good deal. :) (It is pretty much a landmark itself). This hotel is the birthplace of the Boston Crème Pie and the Parker House Roll. It is located near the financial district, the Common/Public Garden, Faneuil Hall and Quincy Market.
For my second trip, I stayed at the Hotel Buckminster. It is over a hundred years old and is located pretty much next door to Fenway park. I highly recommend this side of town- especially if you do a girl's trip like we did (hence, wanting to feel extra safe). While all of Boston is safe and wonderful, I loved this area because at night it was lively. You could leave the hotel and be around people- a lot safer feeling than if there was nobody! (besides Fenway, Boston College is also located around the corner which is why you get the lively atmosphere.) However, it is on the other side of the city that the other hotel is. Basically, you can walk to the sites I listed from the Omni, but you will have to take the T to get to all of that from the Buckminster. (BUT, Boston is nice and small, so taking the T is no trouble at all!)
Boston has this really cool thing called the Freedom Trail. It is a trail marked by red bricks, (and sometimes paint), on the pavement. :
You can walk the Freedom trail on foot: 2mile+ line to see major historical landmarks.
You can book a tour- I have done two.
The Trolley Tour is pretty cool. It allows you to get on and off at each historic site and spend as much time as you want at each. Also, when we booked it, we got a free Boston Harbor cruise. :)
The Duck Tour will show you pretty much the same things, but you can't get off. And since it is a Duck, it will take you into the water as well, but into a different part of the harbor. So, I would recommend the Trolley Tour, but if you can do both, I'd recommend doing both. :) (The Trolley Tour can be purchased for 2 days, so I'd do that at the beginning of the trip and save the Duck Tour for the last day). :)
At the Prudential you can go on the skywalk. It is a little pricey at $25/person, but worth it!
Always, always, always, take the T! NO CABS!
We took the T and walked everywhere, (it is a walking city and so worth the walk. The T just saves time when that is needed.). :) We took a cab once and it was a total rip off! You can even take the T to and from the airport- just find an airport employee and they will send the in the right direction. :)
Sadly, I am the pickiest eater on the planet, so I cannot give good food advice. Pretty much we ate everyday at Quincy Market and at the Shops at Prudential Center, (the mall). Both locations had a large assortment of choices, so I could eat what I liked and my friend could have different choices! lol I ate Regina Pizzeria for most meals. Totally worth it though since it too is a "landmark," and really good. :)
I have not done this, but it seems fun. Check my post, The Paint Bar for more information.
The Common and the Public Garden are must sees! Be sure to see the Make Way for Ducklings statue and ride the Swan Boats in the Public Garden. :)