The Amphitheater at Clark County has done a pretty good job of getting major bands to come out here in the past two years. A number of country singers have been, and Coldplay will play here in August. There's something about sitting on the grass in the summer and listening to great music that's so appealing...only the seats on the grass are horrible, because you have almost no view of the stage. The three large TV monitors help, but they're impossible to see until it gets completely dark, which is always after the concert starts. There is reserved seating, which is $20-50 more, but that kinda takes the fun out of the whole amphitheater thing--after all, you can sit in preassigned seats at every other concert on the planet.
On the up side, the concessions are good--albeit expensive. There's a bunch of gourmet food for sale, and unlike other outdoor venues I've gone to, they have REAL indoor bathrooms with running water.
The worst thing about the Amphitheater is the parking lot. There's plenty of space, but only ONE exit. So at the end of the show, you've got 10,000 people competing with one another to leave from the exact same place. It's a disaster; I've been stuck there for > 2 hours after the show. For most shows, there is a bus you can catch for $5 per person. I heartily recommend this, as it alleviates the traffic mess almost completely. If the bus doesn't work for you, prepare for one of the worst traffic jams you've ever been in.