Oh, and konnichiwa posted this video a few days ago in another thread:
Yoko Shimomura - Hiraki, Kingdom Orchestra Instrumental Version (Kingdom Hearts)
I never played the game, so I had never heard its music before and I think this theme is great and epic.
Just as her main theme for the 2nd game:
Yoko Shimomura - Passion, Kingdom Orchestra Instrumental Version (Kingdom Hearts II)