At the risk of sounding like a salesmen, I highly suggest high fidelity earplugs. They don't hardly distort the music and make it possible to communicate to your friends in the middle of a gig. And for me it is a no brainer, I love music and I wish to continue to enjoying music for a very long time. I also use them for when I play loud gigs. Muse don't just wear their special plugs for monitoring reasons (especially with fuzz factory that creates that beautiful noise at so many frequencies).
Like I said before I use ER-20's and swear by them ( so do every one of my friends who has used them), especially at festivals, you can last longer (which the longer with loud noise the worse the damage) and they come with a case that works great in your pocket between sets. So at least put in normal earplugs for the opener if you aren't there for them. And hey they actually look cool, or at least to me, although I use the clear pair most of the time and they are hardly visible.