Thanks all for the advice, and I'll definitely move my hotel accomodations from Kusadasi to Selcuk instead.

One practical tip I got from the eatingasia blog, they're often travelling in Turkey, and they suggested getting a car rental through Argus Car Hire, which is a consolidator, but apparently they have access to the Turkish rental companies as well, and I was able to get a car at a much cheaper price than through the majors (Hertz, etc).

I'm looking forward to the trip! My first time "driving" in a developing country..