Yep, take the bus.
When I can't get away from work (most of the time!) my wife often uses Pammukkale, air conditioned, 24 TL (one way), couple of comfort stops, 3 1/2 hours, it's a good scenic road, but not a "hairy" drive. Very little traffic.
Bus goes from the otogar in Antalya to the small otogar in the centre of Dalaman. You can get a bus to the Antalya otogar from the airport if that's where you're coming from, or if you're already in Antalya, Pammukkale run courtesy buses from their satellite offices.
Take your camera, there's some nice views from the road.