The only spectacular beach is between Kas and Kalkan and is called Kaputas, in a beautiful cove. Many steps down first of all, after a lazy day also up again!
There are some daytyrips like Saklikent gorge, very nice for kids, you can enter into to gorge and there are donuts for a kind of play rafting. And surely visit one of he Lycian sites!
Oludeniz is also a very good option I agree with Ryburn, the paragliders come down from the high babadag mountain, you can go to Fethiye, what has a very nice harbour, with daily many boattrips to choose from. On tuesday there is a big market.
Visit Kaya Koy either by minibus or wander over the mountain into the abandonned Greek village.
Also Saklikent is within easy reach from here, a must for the kids!