Bodrum-Milas airport (50km / 45 minutes' drive): served by summer charters from UK, including Aegean Flights, Monarch, First Choice, and with the greatest selection of departure airports Thomas Cook and Thomson.
From the airport:
You will almost certainly want to hire a car for your stay in which case we recommend Holiday Autos, who are usually the most competitive price-wise. Otherwise, you could book an airport transfer through the hotel, or take a taxi (about 100 YTL), and use dolmuses (public minibuses) or hotel vehicles for short journeys around the Bodrum peninsula.
By Ferry from Datça:
There is a once-daily sailing (summer only) between Bodrum and Datça, which takes about 2 hours; see bodrumferryboat.com for details. You can take your car on board, allowing you to make a loop Dalaman Datça Bodrum Dalaman, which we did and found strangely satisfying.
Or, if you're really clever, you could get dropped off here at the end of a gulet cruise.