Beer snob here.
I will drink anything if it is free, but if I'm paying for my beer I like less mainstream stuff.
Probably my most mainstream indulgence is Dos Equis special lager with a big ol' lime wedge. Nostalgic for me I guess. Reminds me of some really fun times in Tijuana. I once bought 30 shots of tequila and 30 of these beers for $30 at some bar there. Love it!
Anything that New Belgium brews is great. I love Fat Tire Amber Ale. Right now I'm enjoying some Skinny Dip Ale from New Belgium. Great company, great beer.
http://www.newbelgium.com/
Big Rock makes great beer. Used to love grabbing some Grasshopper and/or Warthog Ale when I lived in Kalispell. I don't know if they brew those varieties anymore or not, but they were yummy.
Also love Blue Moon.
http://www.bluemoonbrewingcompany.com/