We didn't book the tickets for Alcatraz enough in advance, so we had a take a combined city tour and Alcatraz excursion. Cost us an extra $30 each, but it was the only way we'd see Alcatraz.
We both had visions of this dark and mysterious island in the middle of choppy waters. It's not! It was a really nice day and Alcatraz looked like a holiday island. It's only a mile from the Pier, so you can pretty much see right over to it on a clear day. I'd imagine, if it was a dark and dingy day it may look a bit more spooky.