The life in color shows are always one of the best times you'll ever have. For anyone unfamiliar with them: http://www.youtube.com/watch?v=nvpSOFQcp1c
The festival in DC this year is gonna be pretty huge, and is all day/all night. They've also added things like a zipline, water slide, ferris wheel, etc for this one.
From past experience, I'd definitely recommend getting the VIP tickets. They give you a bottle of paint, glasses, a shirt, the soundtrack, let you skip the line, and give you free access to a lockup area to store anything you don't want to have covered in paint.
Tickets here: http://www.ticketmaster.com/event/15004ABDA8AC2A49