I only attended one day of Bumbershoot this year and listened to DJ Jordan and Public Enemy.
DJ Jordan was a unique experience for me this time. I've seen him several times and he's one of Seattle's best local DJs. He was spinning next to the water pond and I got to do my dancing barefoot under a bright sun with water splashing up to my knees.
Public Enemy were also interesting. They played an extremely political show where Chuck D clearly showed where his political leanings lie (getting the crowd to chant "fuck George Bush!"). Of course, anyone who is familiar with their lyrics and shows even remotely shouldn't be surprised, but it was still a good feeling to be in the middle of a large crowd that roared in approval (whether they agreed or not). It was interesting to see the faces of those who didn't want to say the chant (and didn't agree with it), yet couldn't do anything about it given the number of people in favour of the chant.
Both acts are worth catching depending on your venue and location and are extremely unlikely to disappoint.