Well I've been riding street bikes up here for 20 years and my favorite still has to be Angeles Crest.
243 to Palm Springs (through Idlywild is good too).
Fun to take quick trips up Waterman to Lake Arrowhead.
138 through Silverwood then Crestline.
Already took the Z4 through Lucerne up the back way to Big Bear and down the front side.
Also just took it to Santa Barbara from Redondo beach a couple of weeks ago. That was a great trip! Stayed up there for three days with my wife and drove through all the surrounding towns in the hills.