I went to Pelion last summer with friends of mine and we had a great time! Before visiting this magical place everybody told me that Pelion was all about mountains, graphical places full of sightseeings, good food, friendly people and more. However, I realized that the beaches over there were also amazing, crystal waters, not very crowdy, with beautifull sunsets where anyone could enjoy just sitting on the beach.
I strongly advise you to visit Pelion, it is a paradise.