I go to Cincy's Oktoberfest every year. There's definitely a lot of people and some pretty good food and beers there too. My favorite Oktoberfest beer is Christian Moerlein's 5th and Vine which just happens to be local to Cincy.
This region was settled by a lot of Germans so Oktoberfest is a pretty big deal. I know of at least 3 separate O-fest celebrations within 5 miles of each other.
I think my wife and I are going to head up to New Glarus, WI to hit their Oktoberfest this year. I don't think it's all that big, though. It seems to focus primarily on the brews of New Glarus Brewery.
Doesn't really qualify but I just got back from Las Vegas and went to Hofbrauhaus Las Vegas. It was fairly similar to the original Hofbrauhaus in Munich, in decor/building as well as festive atmosphere, just not nearly as big.
The Oktoberfest Goulash was pretty good, the Oktoberfest Bier was good (but was less 'Oktoberfesty' and lighter colored than I expected) and we had a great time.
I never could figure out what that last word is...didn't stop me from shouting/mumbling something the 129 times it was sung while there.
We have no community Oktoberfest celebrations here in Central IL (that I know of), and I'm not about to drive any extended distance to one....besides, Märzen isn't exactly my favorite style. We do have an area restaurant that has a great Oktoberfest menu, and we'll be visiting next week. Been a long time since I've had a fix of Schweinshax'n.
Went to a local brew club's oktoberfest. Was pretty nice. They cut the tickets off at 200 which for Chicago is tiny. Things got a little crowded because of the rain, but other then that think they did a great job. I hadn't joined the club yet so I got to be a partier rather then a worker The beer was arranged in an L so the two pics below are different even the though they look similar.
There are several good fests going on down here in New Orleans this year, which is great news because in the past 10 years I've noticed a surprising amount of really crappy Oktoberfests put on by the major beer manufacturers, I guess just to make a buck.
I stopped going to a major one around here a couple years ago when the only beer I could buy at the beer tent was referred to as a silver bullet.