We were in the group that went to Alcatraz first, this meant we had 2 hours on Alcatraz before getting back on the ferry to go to Angel Island. If you were on the one that went to Angel Island first then you would have more time at Alcatraz as you can return to SF on any ferry.

I went with my friend who has trouble walking. Some help offered on the ferry. We used the accessible transport up to the prison, it was excellent. The staff were very helpful, looking for anyone that may need assistance.
Once at the prison we had plenty of time to look around the prison block, there was even an elevator for those who needed it.

The audio tour is narrated by ex warders and ex convicts. It's very informative. There is plenty of time to walk around and look everything. you can stop the recording if you need more time.

Angel Island was a delight. A tour on an open air bus. Very informative narration with stops for photos. Lots of history and this gem of an island. also time for a light snack before boarding the ferry for return to SF.