Back from SF and wanted to say a quick thanks for all the input. I'll not bore with photos and videos of the trip(!), but everything worked out well. In case it's helpful for anyone elser itinerary ideas fo:

- Arrived into the centre of town and hopped on the no 10 bus to the Toll Plaza for great sunsets over bridge
- Did Fort Point on the Sunday as it's shut Monday. Cable cars very quiet at 8am but very busy 30 mins later after breakfast at Mel's drive-in on Market. Then grabbed a bus toward Fort Point. There are indeed bike racks there. Strolled all the way back via Fisherman's Wharf and up the Filbert St steps to the Coit Tower for great views. Then onto the day/night Alcatraz cruise which is highly recommended
- Bike ride on Monday was quite tough but well worth it. As suggested, collected a bike from the Ferry Building, gentle ride to the bridge and across. Holiday weekend meant the western bike-only path was open for use on the Monday. Steep climb up to the fort, rolled down to Vista Point and again a stiff climb back up to the bridge. Back across the Golden Gate and over Lincoln to Baker Beach. Then a reasonably steady ride along Lake, Clay and Pacific to Hyde and up to Lombard Street. Down Lombard and Columbus to the Wharf and an easy roll back to drop the bike. 24 miles, 1900ft climbed!

Very enjoyable two days and fantastic weather; thanks again for the planning help and thoughtful comments which helped get the most out of the limited time I had around the bay.