One place we made plan ahead for visiting is Alcatraz. I was told that the tickets may get sold out, so bought tickets before the trip.
The very first sign that you will see when you get off the boat.
Alcatraz offer Audio Tour that included in ticket, and it is very well done.
However, If you could catch Alcatraz Garden tour, it is very well worth it! Our tour guide took us around the various restored gardens, and told us a lot of stories about prison, plants and story about various area on island.
After the garden tour, we picked up the mp3 player and headset and head off to the audio tour. it is very well designed.
The info I found said it will take 2 to 2-1/2 hours to visit Alcatraz, but we ended up spending almost 5 hours. You can feel the history in the air.
After lunch, my wife went to attend a session, so I went off to walking around Union Square.