I'm sure most people are aware of this Con, but just in case there are people who slipped in between the cracks, this is the one I went to last year (senior year, I have so many good and bad memories I could go on for 2 pages ).
When: May 22-25, 2009
Where: San Jose Convention Center, CA, United States (ofc)
Why: Pre-registration ends March 31
I'm a huge Super Smash Brothers Melee/Brawl fan (Melee > Brawl just because it takes skill in the former) and they even have an informal tourney, so bring your GC controller if you want in. The players I played are almost at the professional level so it's no easy win.
Aside from that, they'll just screen AMVs, "new" anime, yada yada. You'll probably find yourself alternating between gaming and watching/buying anime.
Pros: Free products (Free Code Geass poster last year!), competitive prices so you won't be forced to choose between 2-3 rip-offs.
Cons in the Con: The line in the beginning was horrendous. My friends and I got there are 7:30 a.m. and it was a 2 hour wait (Imagine if you got there at 9). Plus, by 4:00 P.M. on the Saturday you'll probably be bored and there's 2 hours left before the Masquerades. I only stayed one day since I didn't feel there was much point going the whole weekend.
If anyone else went last year chime in. I've got homework now.