TD Garden is a venue in or near Boston that is most often used for Basketball
If you 're drinking and grabbing food then you have to try either the Fours or Boston Beer Works. Beer Works is a newer spot that brews all their own beer and Fours is a classic Boston sports bar that is a must visit pre or post game. Both have fantastic bar food.
It's a rowdy crowd. I have never encountered anything too crazy, but I'm sure it varies nightly. Security has always been fine. It is far more dangerous encountering drunken fans in the street afterwards.
Sitting in the front of the second tier are excellent seats for the price, in my opinion better than the back rows of the 100 level. Upper deck, the bird's eye requires an eagle eye or some binoculars. If you have to sit high, go close to midcourt. The height of your neighbors could jeopardize your view far court.
The train, T, and walkers dilute some of the driving traffic, but can also put cars at a standstill when they exit. Try to find a spot in the north end and enjoy a digestif before you're party hits the road
Hanover St for the food, the Boston Commons for the people, the Boston Harbor for yourself, the Freedom Trail for some history, the Aquarium for your kids. Ton of stuff nearby, make a nice day or evening of it.
It can be hectic outside the Garden before a game, which makes it easy not be caught scalping, but slightly sketchier. I'd stay away from it if you can, be careful if its necessary.
The Sports Museum, and the Pro Shop are where it's at.
If you have enough time, find parking on Commercial St. down by the harbor. It will give you a nice walk to and from the stadium.
You can get an impeccable meal outside the stadium for a similar price. Can't recommend anything against that.
T or MTBA. For those further out the train is a great option, if you're in the city take the green line. Both conveniently let off at North Station, which is attached to an entrance of the arena.
If you are lucky enough to have a girl who will go to the game with you, take her for a nice stroll down Hanover St before or after the game. You can have a nice dinner before hand, or a slice, a gelato or cappuccino afterwards; it will have the authentic feel of a unique night. If starting at the end closer to the T and Government Center, you will be making your way towards the water. Take a right on Clark St, and it's two blocks to nice dock with benches to relax and enjoy the water. Thank me later.
Hurricane O'Reilly's and the Greatest Bar are the places to be if you're a boisterous beer drinker looking to Paaaahhhtyyy. Lots of nice places on Hanover for a glass of wine and apps if that is more your style.
During a timeout they will do a parachute drop where you can win an iPad. There will also be signups in the hallway where (if you're willing to give away your contact info) you can get your hands on some free gear if you don't feel like dropping some cash at the pro shop.
The young guns will be celebrating a win in full force at Greatest Bar and Hurricane's. Lots of great food options on Hanover with more relaxed bar scenes.
If you can get into the club level, there is a small museum that contains very cool artifacts, like Red Auerbach's winning cigar tossed in a champagne bucket the night they won the NBA title. There is also the newly developed Sports Museum, which is supposed to be very cool.
Bostonians are a rowdy bunch who rally around their teams with unparalleled passion. Expect a few jeers if you're supporting the other team, and be thick skinned, not thick headed, as a temper against the masses could be costly.