First of all, have a happy birthday !
For real indulgence so over to the White Dolphin at Red Island (pick up from Ece Marina) but it is pricey. As is the Levissi and it's a bit hit and miss there and not really kid friendly. For something a little more pocket friendly, the Sundial is nice, or you could look into one of the places up by the tombs in Fethiye which serve a local speciality - chicken or lamb cooked in a clay pot in the oven. If you want to splash out why not hire a boat as many of them do evening trips from Fethiye. There's one from Olu Deniz which goes to one of the restaurants near Gemiler - you can't get to it by road so it's a bit different.