We were in Aruba & Curacao about 3 yrs. ago on Rhapsody of the Seas.(Lovely ship, by the way.)
In Aruba we hired a minivan driver to give us a little island tour. Went to the rock arch at the ocean (quite interesting!) & to see the cacti in the desert; a little church, etc. Then we asked to be taken to a nice beach. He dropped us off at a hotel - maybe the Hyatt? We had a nice, shady lunch on their restaurant patio, used the beach, the restroom & the pool shower (hey, we did buy several nice lunches!) & saw these neat green iguanas or something running all around the pool. Very nice couple of hours! The driver picked us up at a designated time. Cost was much less than a ship's tour. We shopped downtown a little afterward. You can get a lot of the blue & white Dutch Delftware there (but I already had some from trips to St. Maarten!). There is also a Senor Frog's, which, if I recall correctly, was closed, but our l3 yr. olds had to have their pictures taken on the the steps!
In Curacao, one of our friend's daughter's wanted to visit the aquarium. Not very high quality & I would skip it if I were you. (They did do a neat shark feeding, though.) It was just not up to American standards. We did a little swimming at the beach, which was right next to it. Decent snorkeling, but not great & you had to swim out a good distance to find it. This time our cabbie (a lady) did not come back for us. Though there were many cabbies, we waited a little extra time (at least 20 min.) for her. Finally took a different cab, but at least we didn't have to pay for the ride there as it was to be a paid upon completion of the trip! Then we walked around downtown, over the moving bridge; into a few stores. There are some cute bldgs., but overall it was a little disappointing. The postcards make it look a little prettier & it smelled heavily of oil, as there are offshore oil dereks in the area. The weather was a tiny bit overcast, too, though, which may have contributed.
I'm glad we visited those places, but they aren't our favorite Caribbean islands. Many people say Aruba is their favorite, though, so go judge for yourself & have lots of fun!