Gen Con Calls itself “The Best Four Days In Gaming” but they also rate the best four days of cons in my book.
Gen Con was the Uber Convention of the year for 2010 and I haven’t seen any other convention that comes close to competing with them for the title.
If you like gaming, they have every kind of game you can think of and more! Gen Con is where game manufacturers introduce their games to the ultimate gamers. They have the standards of the collectible card games (Magic the Gathering, World of Warcraft, etc.) roleplaying games (Dungeons and Dragons, Pathfinder, and even a Cold War simulation where I got to be Richard Nixon!) miniature gaming, board gaming (Mayfair was there with people sized board games!) True Dungeon (a people sized role playing game in a class of its own and I survived!)
If you are an anime/cosplay fan, in addition to the video screening rooms, Gen Con is a great place to meet fellow enthusiasts. When I arrived the night before Gen Con, there were already otaku in the lobby waiting for the con to begin (well, not everyone waited!) Cosplay in the halls of the convention center and the surrounding hotels is a part of the convention and Gen Con has some great props set up for photo opps like the giant Beholder. Gen Con had some of the most amazing costumes and was the most well organized and best executed masquerade I saw in 2010.
If you like zombies and other forms of terror, their zombie walk was excellent with makeup artists ready to zombify you if you didn’t bring your own. Lloyd Kaufman, president of Troma (home of The Toxic Avenger and other fun films!) was there to teach folks how to “Make Your Own Damn Movie!” and there were showings of My Bloody Wedding and other films.
There were a number of celebrities including the cast Felicia Day, Wil Wheaton, Sandeep Parikh, Tracy Hickman, Margaret Weis, Robin Thorsen, and Jeff Lewis.
If you can only attend one convention in 2011 attend Gen Con!