Staying in a cave in Cappadocia is one of the neatest travel memories I have, though I've traveled to dozens of countries.
#1 - listen to Soleman's recommendations for restaurants, activities, tours, and hot air balloon rentals
#2 - be the last one into the hot air balloon basket so you can see more
#3 - pay extra to go into he Open Air Museum's "dark room" where the best preserved paintings are
#4 - stay here at *least* 2 nights
#5 - if you're also going to explore Istanbul, try to go to Cappadocia on the day you arrive to Turkey, or the day you leave Turkey, so that you don't have to waste extra hours in transit to/from the airport in Istanbul for this extra trip
#6 - get ready for a great tour if you do the Green Tour. Ervil, the guide, is excellent, fun, friendly, and worthy of a good tip
#7 - stop by early to make a reservation at the restaurant Soleman will recommend so that you can order up the meal they make in...