Have only been to these places by car, except did not (and would not ) drive in Istanbul. Driving the other places is quite easy,and then if you want to do Istanbul on same trip you could park in a nearby town and go the last bit by bus.
There are loads of Tourist buses to all these venues in Sept, though most will be round trips.
I think you would find it very easy to go by bus to Izmir. Walk into any tavel shop and book on to next day tours to any or all of Ephesus Didyma Miletos Priene. Then get a bus to Bergama and organise a trip around there and then a bus to Cannakale and book on to a Troy and Assos trip Finally a bus to Istanbul.
You can now buy on line and download Rough Guide and Lonely Planet by sections quite cheaply and they may have better and more detailed options.
There is a lot to see and its all great. Enjoy!