In Aruba, I recommend Clive with Dive Aruba. He has a small 6 pack boat and knows the dive sites inside and out.
In Bonaire, an option is to go to one of the resorts, rent tanks and shore dive. There is very easy shore diving at Captain Don's.
I would also recommend diving in Curacao. We always take a taxi to Dive Bus, rent tanks and shore dive. The entry is just a short walk across the street from their shop. They have a site map and are happy to give an excellent dive briefing. I can't speak highly enough about their service. If you are not comfortable going yourselves, you can also hire a guide to go with you. Curacao is always one of our favorite and inexpensive cruise dive days. We also usually have to go back to the ship for a quick change and venture into town for a couple of hours.