Alcatraz was a beautiful place to photography, in an eerie sort of way. The lighting was unbelievable inside (despite the place's history) and I've always found the interface between humans and nature interesting (it's especially humbling to see how nature has taken back over). Alcatraz has so much history...I highly recommend visiting and bringing your camera the next time you're in San Francisco :).
Muir woods was absolutely stunning. I don't think the photos do it justice!