Links to files of the route:
GPS Exchange Format version (.gpx)
Garmin Mapsource version (.gdb)
Microsoft Streets & Trips v2007 version (works with v2007-2011)
Microsoft Streets & Trips v2010 version (works with v2010 and above)
Microsoft Streets & Trips v2013 version (works with v2013 and above)
Google Maps version in 3 sections:
City Hall to Marina Green, w/Telegraph Hill, Coit Tower and "Crookedest Street in the world" detours
Marina Green to Haight Ashbury, w/ Golden Gate Vista and Haight/Ashbury Detours
Haight/Ashbury to City Hall (using China Basin option) (from what I hear, more pleasant than using 280)
Haight/Ashbury to City Hall (Anatomically correct, uses 280/King)
The crooked bit of Lombard is VERY photogenic, both itself and for the vistas. From the top, late afternoon light is best, tremendous view of Coit Tower and the bay. From the bottom, morning light is best. Parking near there is nonexistant... be prepared to park far and hike back if you want to take photos. It would be extra cool to make 2 loops, leaving someone at the bottom to get a photo of you descending the street the second pass.
If you loop, it's best to turn right on Leavenworth, right on Union, Right on Hyde, then right on Lombard again. You can't approach it from the north (no left turn allowed from Hyde), and trying to cross Hyde on Lombard from the west will put you in a stop and go situation up a steep hill - likely with lots of tourists in rental cars who have many ways to really ruin your day.
The Palace of Fine Arts is better in morning light.
Of course that all presumes sunshine, which truthfully should not be expected.
Tips for motorcyclists:
A rider will have little chance to sight-see while mounted. Staying on the route and avoiding hazards will take all your attention. SF is a very difficult city for riding. Pretty cool for your passenger though.
Some San Francisco grades are VERY steep. Filbert Street and 22nd Street have sections with a 31% slope. And it drizzles or is foggy there a LOT.
Be extra cautious, especially if you are 2-up on a loaded touring bike, unless you are used to accellerating up a steep grade from a stop in those conditions.
Leave a BIG gap between you and the next vehicle, and have an exit strategy already planned, if stopping on a hill. Tourists with a stick shift can get you hurt.
If there is more than one bike in your group, discuss your steep-hill start maneuvers ahead of time, and leave each other plenty of room for screwups.
This is not overly paranoid advice.
Be extra cautious around cable car tracks, especially when wet. They are much worse than train tracks, and you really need to stay on your toes to avoid hooking a tire in the "gap".
Skip the wiggly bit of Lombard St. if it's wet. It's a brick surface with 8 back-to-back hairpin turns on a 27% grade. 'Nuff said. The center especially is very slick.