Here's a few more suggestions, as if you don't already have more than enough to choose from

Did You Know (Don McLean recorded it, not sure if he wrote it)
It Had To Be You (Words & music: Gus Kahn & Isham Jones)
Dream a Little Dream of Me (I don't know writer/performer)

And for a lighter touch,
Side By Side (don't know)

I sang Don McLean's 'Did You Know (that love can grow)' at a friend's wedding, and it drew quite a satisfying amount of sniffling.

~CH.