Arenal D'en Castell, Son Bou, Cala Galdana, Sant Tomas, - all lovely resorts with nice sandy beaches, very pretty scenery and surroundings.
Son Bou has the longest beach on the Island, 4km of gorgeous white sand. It gets very busy near the hotels, but a few minutes walk along and it becomes much quieter. Arenal and Galdana are in beautiful horse-shoe shaped bays, stunningly pretty, but hilly.
I'm not a big fan of Cala'n Bosch or Cala'n Porter. Can be a bit "English" whereas many of the other resorts are much more traditionally Spanish, which I like.