I attended my first Wincon in 2007. I was pretty new to fandom at that time, and wow was it shiny! I hadn't met anyone attending in person. I only really knew my roommate, and I'd talked to one other fan that I planned to meet up with there. But that didn't stop me from buying my ticket and flying all the way across the country. I was nervous that maybe no one would want to talk to me, but I had this feeling that I was going to meet my people. I was right.
The amazing thing about Wincon is that it's full of people who "get it." I don't know about you guys, but I rarely mention fandom to people in my daily life. Not because I'm embarrassed or ashamed of it, but because for most of them, no amount of explaining will make them understand what's so amazing about it or why it's so important to me. When I walk into that hotel in whatever city it is in mid-October, I always feel like I've come home. The call of the wild fangirl in her natural habitat is suddenly all around me as friends, both old and new, recognize each other. It's the internet in live action, but somehow even more. I know a lot of us are most comfortable interacting with the world from behind a computer monitor, but I love getting to talk to fangirls face to face. Because fangirls aren't like normal people. They're so much better.
And now I attempt to be clever/original. So!
Alcohol (but don't worry if that's not your thing!)
Carry On Wayward Son (We may be multi-fandom, but we haven't forgotten our roots!)
Discussions with people who care as much as you do about that obscure point of canon
Escape from RL
Internet come to life
Jazz hands! (This ... more describes how I feel about Wincon, but ... yeah.)
Leopard Porn (but we'll ALWAYS warn for it!)
Memories to last until next year
Over too soon
Queer friendly :-D
Unpopular opinions and finding out you're not alone in them
eXcitement (yes, I did that thing where you cheat on X. It was that or Xylophones, which I have never actually seen at Wincon :-P)
Zero percent un-awesomeness. Only 100% awesomeness. \o/