sudster- are you just heade to the denver/boulder/fort collins area, or will you go all over the state? BTW flying dog is in denver, not aspen. and i dont believe there is any breweries in aspen or the area, used to be one in bonedale but its long gone, so dont bother with that part of the state, the nearest breweries to aspen are all by grand junction/palisade. if youre going to front range area i'd check out wynkoops, breckenridge brewery (which is in denver not breck), flying dog, new belgium, odells, oskar blues, left hand, all the boulder area brewpubs like walnut street, mountain sun, boulder brewing, avery for sure, and theres a new artisan brewery focusing on extremely high quality belgian beers in boulder but i cant remember the name, i know it is a number though, like '23' or something like that...if youre interested in going to summit county then go to backcountry brewery, or at least pick up a bomber in the liquor store wherever you are, i've had each of thier beers once and remembered liking them all, of course sometimes my memory fails me like with this 'alien amber' stuff i picked up in New Mexico last week over the holidays that i haqd at a brew fest last year and remembered being awesome, but picked up a six pack and it is one of the worst amber ales ive ever had. so have fun in denver, be safe, do a quick search and you'll probably come up with some more places to tour, i guess how many you do depends on time. oh yeah one more... fortcollins brewing- their chocolate stout is great, so is their irish red, and the pomegranate wheat is...well...its interesting...you should try a taster of it if you go there or find a pub with it on tap. have fun
edit- also try sandlot brewery at coors field...real good stuff and a winner at this years GABF for best small or medium sized brewery in America. and if youre headed through other parts of the state let me know and i can recomend more in the southwest/western slope areas.