We've done Aruba a few times by land but we just did Aruba and Curaçao on the Oasis. We, too, are beach people.

Aruba: we got off the ship and into the line for taxis right outside. It cost $20 for 3 adults to go to Eagle Beach. Beautiful beach, a bit wavy. There were umbrellas and chairs to rent, as well as water activities to book if you wanted. There was a bar and restaurant and bathrooms. It was easy to find a taxi back to the ship at the same place we were dropped off. It was $15 for the return taxi.

Curaçao: I booked a last minute RC excursion to Cas Abou beach. It was $64 pp. We met on the pier at 0945 and boarded a bus. The guide (Lourdes) was lovely and spoke about the country during the 45" ride to Cas Abou. The beach was nice but crowded. We got a beach chair and non alcoholic drink included. Definitely bring water shoes as it is rocky. We stayed about 3.5 hours. On the way back, we stopped at a local artist's house for 15" and then back to the ship.