The Simple 7th Chords

I'm an avid guitar player. Well I was, when I still had my guitars. Since moving down to New York I haven't touched a guitar because I left them back in Canada to get shipped down. That's neither here nor there. When I did play I didn't really use 7th chords, except for the occasional E7, A7, B7 (I, IV, IV blues) and once in a while a Am7 if I was feeling particularly jazzy. Since getting the uke I feel as though 7th chords are the best thing about that little sound box. In the simplest form, the fingering for a plain 7th chord - not minor, or major, or sustained, etc... - on the uke basically comes down to 4 different "shapes" that can be moved up and down the neck, giving you nice array of variations to use. These shapes look like this:

Shape 2 is admittedly the most awkward to play, for me anyway. I typically stick to the other three. Shapes 1 and 4 are the easiest, just bar that fret with your index finger and use other your pinky or ring finger to hold the other note. simple. I'm still an amateur at the ukulele, but I find having these 7th chords in my repertoire has really helped me spice up my playing. I've been using them to play jazz, blues, or as bridging chords. Maybe I'll record a little something using 7th chords at some point.

What are you favourite chord shapes?
Do you use 7th chords when playing the uke?