Slightly off original topic: I too will be at the beerfest and am looking for a place to eat and have a good brew within walking distance of the trade center; any suggestions?
Come on guys....you totally dropped the ball on this thread.
I'll semi-second what has been said - the Cambridge Brewing Company is fantastic. It is the best brew pub I have even been to, period. Food is really good quality. They have some standard pub beers, but the flip side of the menu is really creative barrel aged / Imperial stuff. The beer garden is a great touch if it is nice out. The only problem - it is on the freaking opposite side of the city from the convention center, and would take three subway transfers to get to. Make that its own leg of the trip, and don't try to squeeze it in around the fest.
Also, I did the Harpoon openhouse once, but unless it changed format, they only offer one true "tour" a week - I think it is Saturday mornings, and is reservation only. They do have times that they open the gift shop for an open house (which is what we did), and agreeing with what was said, they will not ask you to leave. They have at least a dozen beers on tap, and the employees will explain each one as you go. But then they just keep pouring. My wife and I had to basically flip our glasses and call the quits. However, that open house is pretty ridgidly scheduled - I remember going like 3-5PM on a Tuesday. Harpoon might not work, but it is worth a shot.
So to answer the question, you need somewhere to eat before/after your session at the conference (I would aim for eating before). You want good, reasonably priced food, and a really good
local draft selection. You also want to walk from restaurant to fest. The answer is the Barking Crab.
The pictures make it look crowded, but I've never been unable to get my choice of bar stool or high top. But it is really a "dump the seafood on newspaper and eat with your hands" kind of place.
http://www.barkingcrab.com/content/boston.html
I wouldn't call it a dive, but it is certainly casual and low key. I've been there 3 times, and loved it each time. My wife and I always eat outside, and I suggest you do the same. Grab some oysters and a crab cake sandwich, have a few pints of the multiple offerings from Sam Adams, Harpoon, Cape Ann, whatever, and walk over to the fest. It is about a 5 minute walk, and it is a straight shot down the side walk, so no fear of getting lost. From the city, just hop on an outbound Grey line (I think it was grey/silver - it is the underground bus - I was drunk). Get off at the first stop, face the water, and look left (you are basically looking at down town Boston). You can see the Barking Crab, and will know it by the Yellow/Red awning. To get to the Convention Center, just walk back down the sidewalk the way you came from (away from downtown Boston). I followed that advice last year when I attended the festival, and would strongly suggest others do the same.
So some more free advice about the festival (because I think that is where the OP was going anyway).
Don't cross the consumption line before you even get to the fest, because the breweries in attendance bring it strong. It is nice if you can remember what you tasted. Attendees hit heavy with RIS, IIPA's, and Belgian style stuff. It'll catch up with you, and fries your taste buds pretty quickly. I have heard to pick a style and stick with it - probably not a bad idea. Aside from that, I was talking to another member who confirmed the Maine Brewing Company is attending this year. They are a brand new Nano from Portland, ME, and I believe located on the same street as Allagash and Geary's. Find them - they will blow you away. Simply unlike anything else getting made in New England. They could make Stone jealous with their careless hopping rates. And if someone seems to be forming a big line, get on it early. It may be smart to visit DFH, Pretty Things, etc., as soon as the doors open. You start finding youself on a mile lone line and asking everyone around you; "I never heard of these people, is this stuff even any good?" More than likely, yes, yes it is.
Have fun everyone,
Joe