There's not great snorkeling on Aruba, especially from the beach. Arashi is the best, but only fair. Baby beach has always been cloudy when I've been there. If you want to snorkel, I'd take an excursion over the sunken German WWII ship Antilla.
As for driving around, I don't think Aruba offers much in the form or sights. The natural bridge is ok as are the caves on the northern coast. Most folks tend to enjoy Oranjstaed and hopping from resort to resort. On Aruba, the all inclusive resorts are what has made it famous (and their great sand)