Koca Calis is beautiful, I love that end as its less developed, easy quick access to the beaches, abut ideally you would need a car.
I have a friend who lives there who has no car, she cycles everywhere but says the only downside is having to be terribly organised about shopping and not forgetting anything when in town.
She gets taxis when grocery shopping,or going for an evening out, but says that the area and the fact that property is mostly cheaper to buy and to rent offsets the taxi costs.
Ive never lived in Gunlukbasi, I think it used to be more Turkish, but mixed now. Shopping area is getting more developed with more choice, and tends to be a bit cheaper.
Easy dolmus access to Calis and to Fethiye, but quite a walk to the beach if you wanted to walk it.