Sierra Nevada is my favorite brewery. I'm a little biased because I lived in Chico and it was cheaper to drink than it was to eat in that town. Great town, Bidwell park-upper and lower- is awesome, which is the pics on their flagship beers. Great bars, great places to eat, a great town festival every week, great farmers market every sunday, the place is just all around awesome. I miss it sometimes but I'm glad I got out otherwise I'd just be chillin', partying, and hanging out at salmon hole all day everyday haha. Ahhhhhh...
With that said, I think SN has re-established themselves in the past couple years. They have come out with quite a few new offerings to keep themselves in the game. IMO they have a small brewery taste but they're one of biggest breweries out there. Their pale ale is what got me into good beer, and celebration and bigfoot are my 2 favorite beers of all time. If you go to the brewery ask for a palefoot! It's black and tan mix of the pale ale and bigfoot. It's great and wont get you hammered after a couple. It's a brewery, and a town, that is truly worth the trip to see if you can.