I think the flagstone idea will work for your intended purpose. Nice job the cable guys did, jeez 3" deep.
I'm with Ax on the wood deck adding value vs. stone though. it gives a house a warmer, more recreational look. You're right though, it is more work but that's why it's called "sweat equity", lol!
Here's a tip for digging the hard soil here: Water it down good a day ahead of time. You may not even need a pick. :) It looks as though you may have already though, I don't mean to tell you something you already know.
Have fun and keeping posting progress pics!