What to check out first depends on your interest. Also you have to consider some special stuff is at other locations like high-end audio.
I personally don't car much for the car audio - tons will be there, but I do like to check out the cars.
Of course you need to go the E* booth to see what smoke and mirrors they have this year. Last year and the year before they showed the HD-PVR that was coming very soon. Actually talked with one of the 921 team last year about the demo unit they had.
You probably will want to hit D and Tivo to see what they have going. I'm hoping the HD-Tivo will be announced with a price. Then maybe E* will cuts some deals on the 921 .
Of course there is always the Sands for the porn convention in town too if you get bored with the electronics show.
Do you go to Vegas alot? If not, let me know and I can suggest some places to eat.