I would have to agree with above having included these three mountains in my three week USA col bagging trip back in 2013.
I landed in SF and rode Sierra rd + Mt Hamilton day two and Mt Diablo via North Gate am + Mt Tamalpais loop from Fairfax pm day three, after having ridden Old La Honda + Pescadero Creek road +Tunitas Creek road + Kings Mountain road day one.
All three were worthy of inclusion in my trip which included the Eastern Sierra, CO, AZ and finally Socal!
Mt Tamalpais definitely tops in the tourist ticklist with the big trees plus stunning city and ocean views. But didn't feel like a true col due to the dips and rises along the way.
Mt Hamilton is long, though a climb in three parts with the two short descents. Really enjoyed this climb too, even though I nearly died after hitting one of the short descents too fast... I had to straighten up as there was gravel in the apex and just missed the back quarter panel of a car coming the other way plus just pulled up before dropping off down the hillside opposite! After blt's comments about the backside of Mt Hamilton, looks like I'll have to return!
Mt Diablo is the quintessential training hill. Good length and all climbing! Nice views are a bonus. Only downside was keeping to the speed limit on the descent; hands hurt from riding the brakes nearly the whole way down.
All three a little different, all equally worthy climbs!