I am very fond of the Mesa Ampitheater on a perfect Phoenix night. It's got tiered grass, and you just pick a place and park. I like the idea of being able get as close or chill as far back as you like. There is just something about rocking out under the stars and not being all sticky with other people's sweat that I dig about it. Parking can be a little inconvenient if you show up later, having to use street parking and walk, but haven't had to walk more than a few blocks.