The best is the stretch of the 110 freeway between Carson & downtown L.A. (used to ride that corridor daily). The carpool lane is actually TWO lanes (each way, northbound has two diamond lanes at grade, southbound is elevated/stacked).
There's NO better feeling on a motorcycle than being to not only avoid the thousands of lemmings stuck in the traffic, not only being able to use the carpool lanes, but SPLIT LANES
IN THE CAR POOL LANES!!!
I swear I must've passed 10,000 cars a day each way that way. It was so unfair. Always brought a big, giant, schit-eating grin to my face.
You do have to be careful though. Extremely careful.