Finished this earlier, totes agree with how to manage a single day at these events: target a couple of things you want to do early, then browse the Indies.
It's important to experience things you can't anywhere else I think, which for me is VR and talking to devs, and the devs who are typically most available are Indy devs. Obviously just opening a stand at an event is a bit of a risk for any Indy dev, and often a lot of personal passion behind their respective project, and I've found that that really comes across when speaking with them in a warm, welcoming kind of way. It is also great having a go at a game you have never heard of, especially when you hit on something that turns out to be really good.
Not that AAA stands don't talk to you as an individual, or won't field the odd question, but simply because of the demand for something as ludicrous as Guild Wars 2 (there was a 3 hour line for it at Rezzed, what the hell, it is a bloody MMO!?) or anything with a big old wait necessitates that your time is briefer, and the experience a little more artificial.