We spent a nice time at the Isle of Ruegen this Summer, in the coastal town of Sellin.
The Ostseebad Sellin is particularly popular with people looking for beach holidays. They appreciate the fantastic location within the high banks of the beech and the Granitz, the beautifully restored resort architecture, the pier Selllins and - of course: the two beautiful fine sand beaches that protected well against the waves and frequently the prevailing westerly wind.
We stayed at Villa Celia (http://www.ferienwohnungsellin.de): a very nice and recommendable historic house with nice apartments.