Cappadociais, in my opinion, the key region of Turkey. The landscapes are all very impressive and at every new valley visit, there's a new spectacle ahead. You will go past a landscape of volcanic origin formed by ashes and mud, of which the erosion has recreated the silhouette by digging up the valleys. You will discover enormous cliffs, troglodytic villages with habitations in cavities, old churches carved out of the same rock.
Depending on the time, the landscape changes colour, you could spend days looking at and surveying Cappadocia in all senses. I think that it's particularly pleasant to go from one town to the other (such as from Göreme to Uçhisar) by walking on the lover and pigeon valleys. These enable you to do a loop and return to the starting point.
Finally, I advise you to visit the incredible underground city of Derinkuyu dating from the 8th century BC and being able to welcome up to 50,000 people. Underground you can find a real town: bedrooms, churches, stables, refectories...