Insomnia is highly underrated...
Try to check everything out. Sleep is optional. This is JavaOne, after all.
No, really, try it. I admit that, since the first JavaOne, the meeting has become less of a whirlwind, more predictable, more, er, mature shall we say. But it started with all the dot-com liftoff energy, and this means that "mature" is a relative thing. When you're starting from London, being in Amsterdam is on your way to Ufa, but it ain't hardly there yet. And Amsterdam, though quieter than London, is still a lot of fun.
So who needs sleep? Highly overrated, really.
This means you should seek out the stuff the conference is not pushing at you. Java is fun and has spawned a lot of stuff, so you can hear talks that aren't part of the main, commercial line. Or at least your main commercial line. For example, to some the desktop game biz is a biz, but to most of us it's something else. Go listen to those talks. Jini is far enough ahead on Sun's plan that it's a biz for a small, ardent group of folks. Try out a few of them. And so on: A conference focused on a platform will bring together a wider variety of folks. Go to the other folks' talks.
And okay, if you really need to, you can sleep a little.
 The capital of the Republic of Bashkortostan, as I'm sure you knew