I've been to both of those places myself about 2-3 years ago. Unfortunately we missed the last tour at new belgium but got to take the one at O'dells. New Belgium's tasting room was packed and we were lucky enough to find a table to sit and enjoy their brews. I must admit that I prefered O'dells brew over NB'S. Just had a better fresher taste. We also made it to Cooper Smiths there in Ft. Collins also. Me and my dad got pretty smashed there trying out all their seasonal beers they had; must have been like 6-8 different ones. Cooper Smiths is also where I had my 1 and only chili beer. Now, I'm a big fan of spicy stuff, but that beer was just nasty.
Oh, and by the way, doesn't it smell sooooo freakin good just outside of the breweries?