Just back from Hisonaru, 10mins away from Fethiye. Stayed in area few times since 90's.
Fethiye is very much 'bustling' compared to years ago, wouldn't choose to stay in the town now.
Hisonaru is inland and very 'tacky' imo. I stayed there for Aqua Park 2mins down Rd (food/drink extortionate, but park good).
Olu Deniz beach close by is awesome but can get busy, but due to expansion in area, traffic can be a right pain unless you go early morning.
Calis beach is OK, but that's all it really is, around the bay from Fethiye, which is a marina, unless you stay at the nice hotel around other side of the bay.
Elsewhere for beach, look at Icmeler....around bay from Marmaris, nice quiet place with decent beach, all noise is in Marmaris. Was a good, but quite a while back I stayed there though.