what about akyaka, it is also on the way back so you will be nearer the airport, its about 50 mins from the airport and about 25 mins from marmaris. very scenic turkish resort, we have just come back from there a few days ago and its so lovely , it has a lovely sandy beach and is surrounded by mountains its in a conservation area, ive been to turunc and i prefer akyaka although turunc is slightly bigger, have a look at the photos ive put in the gallery

http://akyaka.com/index.php

http://www.turkuaz-guide.net/gokova.html

http://www.marmarisinfo.com/sightseeing/cleopatra.phtml

http://www.akyaka.org/index_eng.htm

http://www.holidaylettings.co.uk/akyaka/

http://www.exclusiveescapes.co.uk/destinations/property/incogn/detail/

http://en.wikipedia.org/wiki/Akyaka%2C_Mu%C4%9Fla

http://www.gatetoturkey.com/turkey_a_z_tour/01015/

http://ourworld.compuserve.com/homepages/ciaranburns/Aktour.html

Try Datca, I have recommended it before so search old posts. Its just over an hour from Turunc and very Turkish. None of the mass tourism package companies go there and it is a little habour town. The peninsula it sits on is stunning and as you have a car you will have great fun exploring there. You could either stay in the town itself and it would be easy enough to find accommodation or stay in one of the small coves further out. My choice would be Hyat Buku for total relaxation. Just turn up and go to Ogun's Place. He has simple accommodation and if full will find you somewhere to stay.
From Datca it will take you just over 2 hours through stunning mountain scenery to get back to Dalaman.

Why not try a gulet cruise. You will visit all those places mentioned but have the advantage of being with a group of people, who will all be your mates by the end of the week