I went to E3 last year for the whole thing, mon-fri. The good stuff isn't really on the floor during wed-fri showings. What you really want is a media pass with preset behind closed doors meetings with the developers. Last year I watched B.C. on the xbox with Snoop Dog...behind closed doors with the developers about about 4 other people. Was also one of the few that got to see Fable up close and personal.
Waiting inline for hours to see the HL2 video, or Halo2 video is pointless IMO and a waste when there are so many other things that you won't be able to download videos of later going on.
I think you can easily make up your $100 in t-shirts and other swag. And if you can, get invited to as many parties as you can. Nvidia's party last year was quite cool, plus you got a very good 'gift bag' of goodies, games, backpacks and t-shirts.
All in all it was fun, but I passed on going this year. I'll probably go again next year to check out Xbox2 and PS3.
Oh and just know that when you first walk in, you will be in sensory overload.
