I'm in...Ch'ville and Vegas too! Excited to see Muse too but not so much for the Black Eyed Peas, eh, maybe I'll be surprised.
Was in the pit at a show over the summer and it IS first come, first served, however, the stage is very high, so depending on what you want to get out of the experience and/or how tall/short you are, it may or may not be for you. I plan to be there.
If you follow the Going Out Gurus chat on WaPo they are going to cover the logistical details in Thursday's chat. Probably just metro and traffic stuff. Then I'm sure they'll post a lukewarm review in the Style section later in the week.