The first time I went to E3 was in 2001. I was only 17 at the time and the expo required that you be at least 18 years old to attend, so I had to borrow my older brother's ID. I actually called in sick to school that day and my father took me to the show.
After reading about E3 for several years in Nintendo Power and other gaming magazines, I finally got the chance to see the show for myself, and it was like experiencing a theme park for the first time. It was actually overwhelming. But I had previously been to the Los Angeles Convention Center for a car show that my father wanted to attend, so at least the building was familiar.
E3 was interesting because both the GameCube and the original Xbox were releasing later that year, and they were playable at the show. The Super Smash Bros. Melee section was absolutely packed, and even the Luigi's Mansion section was rather crowded. However, I did get the chance to play Wave Race Blue Storm, which as I recall, had only a single screen off to the side from main games. I think Mario Kart Super Circuit was also playable.
I ended up getting all sorts of free stuff including shirts, hats and whatnot, and there was even some company in one of the hallways holding a large ring with a shower curtain hanging from it. If you were willing to take off your shirt and put on one of theirs while they covered you with the shower curtain, you could get a free shirt. We did that, of course.
There are a lot of specifics that I am no doubt forgetting, but long story short, it was a ton of fun.
I took pictures of the event with a crappy disposable camera, so they're not the greatest quality, but they're better than nothing. Someone on my Youtube channel asked me to post the pictures, so here they are.