There are many nice beaches in Cabarete/Sosua. Go to
www.activecabarete.com and you will find many (go to the activities section and click excursions). One that is not mentioned and that I like going to is Encuentro beach.
If you want to go a little bit further try the samana area. Beautifull beaches there.
You can find a lot of info on this site about cabarete. Also about restaurants.
Kukla