I went to Magic in 2008. tp is right, set up appointments before or you'll be on the outside looking in.
I've known several people that go to "watch" the first year, so they know what to do the second year.
Magic, Pool, Source, etc. is often where you go to meet that guy that you've spoken to on the phone or have already had correspondence with.
You will be overwhelmed with the talent there. I went as a buyer. Those guys are on auto pilot, as they go over their line with you. How fun can it be to show the same pieces in their line 40 times a day. It is interesting to see which lines have a real passion about their stuff v.s. looking like they've spent too much to cancel now.
You can find anything you need there, printers, cut-n-sew manufactures, custom denim, whatever apparel services you need.
The bigger lines will have celebs on hand to generate buzz about their stuff too.
Besides, it's in Vegas, so it can't suck!
Here's some stuff I printed for guy in 2009 that showed at Magic. This guy does custom sneakers for Nike and celebs. All the shirts you see in the photos were done by me: