Istanbul and Cappadocia make a rewarding first week because they ask for different kinds of attention: imperial courtyards and neighbourhood ferries in the city, then rock-cut churches and open valley walks on the plateau. Three nights in each base leave two full sightseeing days per region, with day four reserved for the flight and day seven for departure.
Start in Sultanahmet or Sirkeci for the Historic Peninsula. Spend the other city day across the Bosphorus, rather than adding another chain of ticket queues. In Göreme, keep one day local and arrange one regional outing for an underground city. Ballooning is an optional dawn activity; the land programme remains worthwhile without it.
The six-night plan assumes a flight home from Kayseri or Nevşehir, directly or on a protected onward ticket. A separate-ticket return requiring an Istanbul hotel extends the trip. Spring and early autumn suit the walking emphasis; late October needs warmer dawn layers and shorter afternoon hikes.