I quite liked Harajuku O_o Possibly because there are a lot of fairly cheap clothing stores around there, and I was interested in taking photos of the cosplayers. If you go in thinking its some kind of wonderland where everyone is a cosplayer you'll be disappointed, but if you're realistic about it and have some idea of what it actually is, it can be fun
It's interesting seeing all the people in alternative fashion - sort of the flipside to the older and more traditional aspects of Japanese culture. I think the guys in our group were far less interested though - Harajuku is more fun if you're a teenager/twenties girl who can fit into the Japanese clothes, otherwise I can imagine it would be a bit boring.
Yoyogi Park and Meiji shrine were really beautiful and peaceful though, interesting contrast to all the hustle and bustle just outside it.