7 days: Istanbul and Cappadocia

Days 1-4: Istanbul (Sultanahmet's mosques and palaces, the Grand Bazaar, the Bosphorus ferry, a Beyoğlu evening). Day 5: fly to Cappadocia. Days 6-7: the balloon flight, the Open Air Museum, an underground city, a valley walk.

10 days: the classical circuit

Days 1-3: Istanbul. Day 4: fly or bus to Izmir; Ephesus and Selçuk (days 5-6), with Şirince. Day 7: Pamukkale and Hierapolis. Days 8-9: Bodrum (castle, gulet cruise). Day 10: back to Istanbul or onward.

14 days: the grand tour

Istanbul (4 days), Cappadocia (3 days: fly via Kayseri), Antalya and the Turquoise Coast (4 days: Aspendos, Side, Ölüdeniz or Kaş), Ephesus and the Aegean (3 days). Domestic flights stitch it together; the high-speed train covers Istanbul-Ankara-Konya if you add Konya.