It’s a day of tie dye and top 40 as the faithful descend upon the two L.A.-area arenas.

Jerry Garcia might have died 15 years ago, but ambling through the parking lot of the Forum on Saturday night, you'd have been hard pressed to know he's gone. Two hours prior to the Dead's first L.A. show in more than a half-a-decade, the sun-scorched asphalt was already swarming with people. The scene was a cross between a Renaissance Faire, a Bedouin crossing and the world's most pot-addled family reunion.

Limousines ferrying baby boomers idled next to withered Winnebagos still following a band that first formed nearly 45 summers ago. Rusting school buses cloaked in rainbow Day-Glo paint were packed to the gills with AARP-aged hippies - the strains of "Scarlet Begonias" mingling with the smoke from dirty windows.

Not so far away, at the Verizon Wireless Amphitheater in Irvine, a very different kind of arena show was underway: KIIS-FM's Wango Tango, a top-40 blowout featuring Lady GaGa, Kelly Clarkson and the Black Eyed Peas, in addition to a host of other radio-friendly favorites, attended by hordes of screaming teenage girls.

The weekend concerts illustrated two opposing approaches to being a devoted music fan in today's pop culture landscape: Either embrace every genre and artist with the same open-minded ardor or single-mindedly invest all your energies into the one performer, group or style that defines you.