Butterfly Kisses - Bob Carlisle. BAWWWWWWWWWWW--
My daddy and I used to dance to that song all the time when I was little. It's an instant waterfall of tears every time, I don't care how cheesy it is.
Into The West - Annie Lennox.
This was used in The Return of the King. Absolutely beautiful. Yeah, I cried.
Edit: Oh, and how could I forget!
All Love Can Be - James Horner, A Beautiful Mind soundtrack
Title is mega cheese, but oh my. That movie was another waterfall of tears. The song is icing on the cake.