These are some songs that have great guitar riffs.
Stairway to Heaven by Led Zeppelin. I can listen to this song anytime.
Guns N' Roses - Sweet Child O' Mine
Born to be wild - Steppenwolf
Jimi Hendrix - Voodoo Child
I love this song. excellent riff and excellent solo
Joe Satriani - Satch Boogie
Another great riff and amazing song by Joe satriani.