Istanbul is a great shout . A great city to keep going back to.
I’m back there next week but only for a weekend .

I’d also recommend Andalusia. Fly to Malaga, take in Granada, Cordoba, Seville, Jerez and Cadiz. It can all be done very simply by train too so no faring with a car. It does get extremely hot though so bear that in mind and there’s no sea breezes to cool you down .