Fethiye is the nearest largish town to Calis just across the bay.If you took the water taxi last time it sounds like you went to the Tuesday market which is in Fethiye.I would agree with the Saklikent/Tlos,suggestion.We took a jeep safari(Karacaye Jeeps I think)which went to Xanthos,Tlos,Yaka park,Patara and Saklikent ,long day but great and well worth it.A day or two just wandering round Fethiye,the harbour,marina, Pas partur etc.Or Fethiye at night could include a visit to the fishmarket where you choose your own fish or seafood and take it to one of the many restaurants surrounding the market where they will cook and serve to you(we all have our favourite restaurants here so Iam sure members can recommend)There are many other restaurants in Fethiye to try and there are plenty listed on this site.If pubs are your thing Fethiye is also good for a few beers along bar street in the Pas Partur.Loads of boat trips run from Fethiye marina but I would advise the Blue Bays boat trip from Calis Boat,a full day in and out of small bays,swimming(for those who want to) and sunbathing,a fantastic lunch on board and afternoon tea.You could go to Olu Deniz for the day to see the stunning lagoon and beaches,have a party night in Hisaronu or you could just wander around Calis doing anything that takes you fancy ie beach,waterpark,bars,restaurants,sunday market,sunsets etc.etc.
Iam sure you will find plenty to do