Here's another day-trip loop that gives you a great view of Cappodocia:
Derinkuya Underground City--An amazing underground structure that consists of 8 floors--go early in the day before the crowds.
Soganli Valley--Traditional village where people have built homes in rock cones. The locally-made doll is the emblem of the village and is sold by local women.
Sobessos--Newly discovered Roman archaeological site with excavations still underway--especially beautiful mosaics.
Keshlik Monastery--Take a flashlight to view the frescoes.
Mustafapasha--See old stone Greek houses.
AND, if that isn't enough a 3rd day could be used for hiking in Ihlara Canyon.
We got a nice map of the area from a tourist agency that I'd be happy to share.