Quote Originally Posted by -N-
Aeris's Theme would work well. If only they had done that.
What -N- said. Though I saw a fan-made FFVII music video with Evanescence's My Immortal, and that one worked pretty well in the scene when Cloud buries Aeris in the water:

I tried so hard to tell myself that you're gone.
But though you're still with me,
I've been alone all along.
When you cried I'd wipe away all of your tears,
When you'd scream I'd fight away all of your fears.
I held your hand through all of these years.
But you still have...
All of me.