If you're thinking about shaking your tail feathers to the electronic dance music at PacificSound's Sunset Party opener this Sunday, April 25, at Stafford Lake Park in Marin, consider putting safety and the environment first by taking the bus there. Not just any bus, mind you. I wouldn't suggest you jump on Golden Gate Transit in scant party attire and a few open bottles of booze. TransportedSF's tricked-out biodiesel buses, which seat 40 adults each, come complete with dancefloor, state-of-the-art sound system and film projector. Lucky you, they're headed for the Northern California-style hoedown this weekend, picking up passengers in San Francisco at 12 noon on-the-dot at the Revolution Cafe, 3248 22nd Street. $20/passenger covers the round-trip fare.