This is a tune I made up, trying to include as many shapes for 7th chords as I could think of. It doesn't consist entirely of 7th chords though... that wouldn't sound too nice.
 
There are two versions of the tune, a simpler one for getting started with the strumming pattern and barre chords and the actual tune I came up with. They both have the same structure, but the latter has more fancy and variable fingering.
 
Without further delay, let's take a look at the shapes of 7th chords in standard tuning:
020100 , 002020 , 002223 , x1102x , xx2130 , (2)2120x
These are the 6 shapes of 7th chords that I use. On the left end of the shape is the 6th string, on the right is the first string. The way they are shown they are not all in the same key. The root spot for each is marked with underlined font.
 In order to make the tune a bit more interesting I substitute some 7th chords with  7#9 chords. The presence of both the major and minor 3rd in these chords gives them their edge. I use 2 shapes:
xx1022 and (2)2123x 
Finally there are some standard minor and major chords to keep it balanced.
 
 
Enjoy!
- RG -