Boulder Beer
Boulder Beer, (http://boulderbeer.com/). Claims to be Colorado's first microbrewery, but there is no doubt that their beers have been around forever in Boulder. Brewery/Pub is in north Boulder in what always seemed an odd location near the train tracks and off of Valmont near Foothills Parkway. They make great beers and have excellent happy hour deals.
Walnut Brewery
Walnut Brewery, (http://walnutbrewery.com/). Many classic beers that Boulderites rave about years after they leave Boulder. Located in the heart of Boulder on Walnut St, near 11th. Parking can be a pain in this area; best to use the parking garage across the street and hope for validation of your ticket.
The Sink
The Sink, (http://thesink.com/). The sink is a Boulder institution with its colorful walls, great food and stories past Robert Redford was the janitor it attracts a large crowd for burgers, beer, gourmet pizza, and drinks almost every day of the week. Bring a black magic marker, and you can sign your name on the ceiling like generations of graduating CU seniors. Do not write on the walls, though.
Mountain Sun/Southern Sun
(http://mountainsunpub.com/). two locations in boulder for your delight. the original mountain sun is on the east end of pearl street while newer location, called the southern sun, is in south boulder at the intersection of south broadway and table mesa in the table mesa shopping center. some excellent beers particularly the java porter and often excellent boulder granola music. remember that it's a cash only bar.
Red Fish Brewhouse
Red Fish Brewhouse, (http://redfishbrewhouse.com/). Classic small-scale brewpub in the heart of Boulder. New Orleans style food, great happy hours, and they even serve an organic beer Tree Hugger is a great try. The restaurant has one of the largest big-screens in Boulder to watch the game, and small local bands in the evenings. Located on 13th and Spruce, one block off Pearl Street and across from the Boulderado Hotel.