In Des Moines, the best place to sample microbrews is (sadly?) not a microbrewery, but El Bait Shop. They have, at last count, 106 beers on tap and a wide selection of bottles (including stuff from Peace Tree and Olde Main, mentioned by others). One of my favorite things to do is go in early (necessary if you want a table on the weekend) and order a beer flight.
I echo all the recommendations previously posted. Court Ave. has very good beer, food is pricy but very good. You can't go wrong at El Bait Shop for selection. I was AMAZED at the hard-to-find offerings they had on my first visit. I'd give Racoon River a pass, but I will recommend the Rock Bottom in West DM. I know, it's a chain, but they have a brewmaster who makes a lot of his own recipes and they are awesome. We've never had a problem with the service, but we usually sit in the bar area and can fetch our own beers at the bar if we need to. Have fun!
I agree that Rock Bottom in West Des Moines is surprisingly good, for all that it's a chain restaurant. I had a beer with lunch there a couple of weeks ago and was impressed enough to make plans to go back. The waiter also let me sample two of their cask beers free of charge (both were very nice). Now that's a way to earn a long-term customer!
Court Ave has some great wood aged beers. Peace Tree in Knoxville is putting out some really good brews right now too. I'd stay away from Old Main, their mass produced beers are awful. El Bait Shop has an incredible selection on tap, and if you go on Thursday they have homebrewers giving samples too.
I = agree w/ the only brewery's being in west des moines are the rock bottom & the 2nd best one is the Granite city. I didn't know that (" but not your traditional brewery as the wort is trucked in" They still serve a nice choose of brews though.
[FONT="Book Antiqua"]I was once told to *"To keep from the pain, You must Think before you Do."]
A couple buddies and I went to Hub City about 2 weeks ago on a Friday. We are homebrewers and asked if we could tag along while they brewed during the day. It's a family run business and I can't begin to say just how welcoming and friendly they were. I'd definitely recommend checking it out some time. They give tours and have a nice tasting room.