Most of the best beer bars are in Cambridge and Alston/Brighton, not far from Boston, depending on how much time you have for your 1 day. The Cambridge Brewing Company is probably the highlight. It's close to downtown Boston by subway, close to the Kendall Sqare T-stop, if you only have time for 1 place, and it's only a few blocks from Lord Hobo and Meadhall, which have a broad selection of regional and national beers. My favorite place is probably Redbones, a barbecue place with a great beer selection, just a few minutes from the Davis Square Redl Line stop. In the Alston area, Deep Ellum is my favorite.