Bridge Over Troubled Water, either the original Simon & Garfunkle version or Celtic Woman’s version (on their Believe album from 2011)
Virtually anything by Enya
Celtic Woman’s version of You’ll Never Walk Alone (very uplifting)
Also:
San Francisco (Be Sure to Wear Flowers In Your Hair) by Scott
From Great Britain to LA. It Never Rains In Southern California and The Air That I Breathe by Albert Hammond (The Hollies version of the last song is even more uplifting & awesome)
There are undoubtedly many more songs that answer this question, but their titles & artists somehow aren’t popping into my head right now. (Perhaps the fact that the afternoon is getting toasty warm (low 90s Fahrenheit) & I still have my windows open & my a/c off.)