Fethiye is very lively, lots of shops,bars and restaurants, nice marina, large market. Lots of boat trips, BBQ trips etc.

Depends what you are into, quite a lot of history, some Lycian tombs and several arceological sites.

Nearby is Hisaronu which you can use a dolmus [minibus taxi] to go to. This is full of hotels, bars discos etc and is very very lively. The local jewel in the crown is Olu Deniz which has a large beach, then a nature reserve beach and best of all a beautiful lagoon as well as shops, restaurants, hotels etc.
Nearby is the ghost village of Kaya coy, quite eerie and well worth a visit.