Ortaca is the name of a town and district in Mugla province, its name meaning "the town in the middle." It comprises the holiday resort towns of Dalyan and Sarigerme, both within easy driving distance of Dalaman Airport, unlike Marmaris and Fethiye (which are both at least a 1 hour drive away). Neither Dalyan nor Sarigerme are as built-up as Marmaris which is why they attract tourists looking for a more relaxed holiday atmosphere.
In Dalyan, begin with a leisurely boat cruise along the Dalyan River to see the Lycian tombs built into the nearby cliffs (dating back to 400BC), Koycegiz Lake, the mud baths and Iztuzu Beach, a breeding ground for the endangered loggerhead sea turtle. Also think about visiting the markets at Koycegiz; the biggest bazaar in the region.
Don't miss the ruins of the ancient city of Caunos, on the riverside facing Dalyan. The most important monuments are the acropolis surrounded by city walls, the theatre, the agora, the temples and tombs. Caunos was founded around the 9th century BC and features excellent examples of ancient Lycian architecture.
It's a good idea to rent a car so you can explore as much of the region as possible. While there are dolmus (the local minibuses, very cheap) these will only get you so far.
Avoid any restaurants that display pictures of their food outside alongside claims they serve "traditional Turkish food." Probably not the most authentic dining experience you can have...
Turkish food is simply delicious and despite an incorrect greasy kebab image, Turkish cuisine is actually fresh and healthy too. Start with a platter of hot and cold meze, (an assortment of appetisers which can include dolma stuffed vine leaves, humus or stuffed aubergines), before sampling a grilled meat or fish dish accompanied by some kisir - a side salad of fine-ground bulgur, tomato, parsley, onion, garlic and lots of spices. Finish the meal with a sugary sweet Turkish dessert such as baklava, sutlac rice pudding, or helva cilik (a rich, sweet paste with crushed sesame seeds, nuts, sugar and honey). If all of that is too sweet, try the delicious cheese on offer such as the white variety known as beyaz peynir (like Greek feta) or the very salty hellim (halloumi). Meanwhile, a popular snack is the gozleme, a savoury pancake stuffed with meat, cheese and/or vegetables such as spinach... Afiyet olsun! ("Enjoy your meal" in Turkish).
Of course you can always bring some lokum (Turkish Delight) or apple tea to share with the folks back home, but why not pick up a beautiful handicraft such as a hand-painted ceramic item for your home? For those with the means, there are some exquisite kilims(tapestry woven carpets) on sale. But, bargain, bargain, bargain!