Here’s an interesting progression found in a number of songs. Listen to Lee Brice’s song Love Like Crazy to hear it (see Youtube video at the end of this post).

The example in the key of G is G, Gmaj7, G6, Gmaj7 and then repeats:

G-Gmaj7-G6-Gmaj7

Here’s perhaps a better sounding way to play this progression in the key of G:

   G Gmaj7 G6 Gmaj7
e:-3---x---3---x---|
B:-3---3---3---3---|
G:-2---4---0---4---|
D:-5---4---2---4---|
A:-5---x---x---x---|
E:-3---3---3---3---|

Listen to this progression in the key of G:

Now try it in the key of D:

D-Dmaj7-D6-Dmaj7

D-Dmaj7-D6-Dmaj7

Listen to this progression in the key of D:

Listen to what the progression sounds like in Lee Brice’s song here in the key of Bb: