I posted this in the GABF thread for those visiting the city, but I'll post it here as well for your information.
Renegade Brewing Company
. My favorite local brewery.
Wit's End Brewing Company
<---IMO, they make the city's best Hefe
River North Brewery
. They primarily use Belgian yeasts in their brews, so if you're into that sort of thing be sure to check them out!
Strange Brewing Company
. In a quirky spot under the interstate, but they always have something creative on tap or firkin.
Copper Kettle Brewing Company
. A little further from downtown, but nearly everything they make is grade A solid.
TRVE Brewing Company
. Brand new brewery just a hop and a skip from downtown, just a few months old but demand for their brews is high.
. English style brews on tap and in casks.
. Most should be familiar with them.
Bull & Bush
. They recently took home 4 medals at the World Cup, plus you can do tableside hop infusions!
Del Norte Brewing Company
. Mexican style beers. They just opened a new tap room.
Dry Dock Brewing
. Previously mentioned in this thread. Kinda far from downtown in Aurora, but they have a lot of taps and a huge tasting room.
Vine Street Pub
Sister to the Mountain Sun of Boulder, they recently opened their own brewery. FYI, CASH ONLY, so be prepared.
Caution Brewing Co.
Yak and Yeti
. This is actually a Indian/Nepalese restaurant, but they also make their own beer.
Golden City Brewery
. Located in Golden, their tap room is crazy tiny, but they have a large backyard patio with great views of the mountains. Second Largest Brewery in Golden, CO!
Great Diving Brewing Company
. No need to explain. Go get some Yeti.
Wynkoop Brewing Company
. Conveniently located downtown, plus they have a full kitchen unlike most of these other places.
Also, there are plenty beer centric bars in the area:
The Cheeky Monk
. Lots of Belgian imports on tap plus a few hard to find American craft beers.
. They are attached to Stranahan's Distillery but have 20 taps, 19 of which are dedicated to Colorado breweries. Plus you can try out beers from places like Elevation Brewing Co. or Crazy Mountain which are kinda far from the city or Prost Brewing Co. which isn't even open yet! Food is awesome as well, buffalo or lamb burger ftw.
Ale House at Amato's
Awesome patio and tons of taps.
Falling Rock Tap House
. Duh. They probably have the most selection of any place in the city.
. They're trying to upseat Falling Rock as owner of the most taps, I don't think they're quite there but they are close.
Euclid Hall Bar & Kitchen
. Great food, lots of selection beer wise.
Has a dive-y feel, but looks can be deceiving. They consistently have a wide and varied list of beers to choose from both on tap and in cans.
. Not too far from downtown located on Colfax on Cap Hill. They have about 6-7 taps with usually one on nitro, however their bottle and can list is huge.
Highland Tap & Burger
. Good food. Nice patio. And again, lots of beer.
As far as breweries in the mountains I'd say Crazy Mountain Brewery in Vail or Elevation Brewing Company in Poncha Springs.