been 3 times but '94 was the most recent. Ephesus, Pammukele, Kappadokia & Istanbul (and Bosporus) are the must-sees, but that's a big matzo covering several hundred miles. we got lucky in Izmir looking for a personal guide to Pammukele and we ended up going wherever he felt like driving us for the next ten days.
you could do worse than Alanya, but it might be a little too far east to be a base. but you got the right idea - somewhere between Bodrum & Alanya would be the best nexus to both enjoy & explore from.
the greatest things about Turkey were the citizens and that fact that it may have been the actual Cradle of Civilization and nobody told the world. our guide took us to many of the ruins of major sites in SW Turkey that had yet to be worked by archaeologists - there are hundreds of them. he also took us to share slices of real life with people who'd never talked to an Anglo (and since one of our party was a 6ft blonde girl, that was really sumn). he also took us to several coves that would be worthy of highrise development in Mexico,that had two sheepherders and six hippies within 10 miles of us. i imagine that Turkey is gone, especially after 9/11.
i'd definitely approach my research in chatrooms or whatever - the Mediterranean (especially the Aegean) has always been trekker country and they rarely failed me in several trips keeping me hip to what's new & next. GL - worth the trouble.