We very much enjoyed Ephesus Tours as our local tour operator in Istanbul and Kusadasi. Young, personable, knowledgeable, and very accommodating staff. Nice website, too:
In Athens, we enjoyed George, "the best taxidriver in Greece." George is not a licensed guide, but he is delightful, a great driver, very accommodating:
GEORGE Kokkotos Cell: 011 309 322 05887 Fax: 011-301-502-4482
I can highly recommend Ren's tour in Katakalon (Olympia), too. It was awesome!