I would reccomend just taking a taxi tour of the island. Go to the Natural Bridge and Aloe Vera factory. Then to the beach. There are watersports available there. Very nice beaches. Arrange to have to same taxi pick you up at a pre- arranged time. The taxi drivers charge about half what the ship tours are and are just as good.
Also do a little shopping. I loved Aruba. The island is so clean and the people are so freindly and helpful. I definately want to go back there again.