I Cross My Heart by George Strait is in Ab at 66 beats per minute and runs 2:56 across 26 bars. It uses 12 chords — Eb, Ab, Fm9, Bb, Cm, Gm7, Fm7, Bbsus, and a few more. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? I Cross My Heart guitar melody tab.