I have been using a pressure washer to wash my bike since the day I got it, I have never peeled off any graphics or damaged any bearings, its just a matter of being smart about it.
I wash the bike with a pressure washer, take a degreaser or contact cleaner of my choice and hit the greasy spots, pressure wash it again, anything else, like chain lube thrown on the plastics, wd40 will easily take care of. I then spray down the underside of the fenders with wd40, it helps keep mud off a little bit better, and then apply the polish (
http://kalgard.com/products/proddetail.asp?prod=762780%5FO1615 ) my choice to the plastics.