The coaches are excellent cheap and frequent infact we are travelling from antalya to marmaris on tuesday for 40 lire each,the pamukkale lines seems to have the best reputation,i should imagine the trip would take around five hours via mugla with a few stops along the way,just enquire at fethiye bus station there usually is no need to pre book you just pay and ride as you would here.flying is not an option really as you would have to go via istanbul we were considering going to syria for a week and then flying from aleppo or damascus to dalaman but all routes led to istanbul first the same with antalya,however the current political situation and visa restrictions have put a stop that sadly.good luck