I'm pretty much like Big D where the game and soundtrack have to be tied together for me to appreciate both. Chrono Cross has a great musical score, but I consider it a lousy soundtrack cause it only has a handful of tracks that I felt were strongly tied to the story.

It has taken me a awhile to think of one and then it finally struck me, Xenosaga Episode 2. It's a pretty subpar game but the music for the cutscenes done by Yuki Kaijura are superb.