Hi Alan,
I have been both to Bonaire and Cura?ao twice in the last 8 years, and long to return! I would, as other posts recommend, state Bonaire as being favourite. The ease of site access is legendary, and second to none. You can dive 365 days a year, 24/7, just pick up a tank or two and go. You can review trip reports for Bonaire and Cura?ao on this very website, at <a href="http://www.bsactravelclub.co.uk/where/index.html" >http://www.bsactravelclub.co.uk/where/index.html</a>.
I have heard of the Lion Dive resort, and Carib Inn as being very good. I have always stayed at Capt'n Don's Habitat, which I rated very highly on the Accommodation/food, and the dive operation is one slick marvel. I have not been there however for 4 years, and have heard that the resort itself has gone a little frayed at the edges whilst maintaining high prices, whilst the dive operation is probably still the best on the island, and I have for this reason included a trip advisor rating for this resort, and others, as a link on this page. You can stay elsewhere and still dive with them, I guess. I hope this helps you make up your own mind.
Cura?ao has you captive of your own resort for diving, which is a pity, because the diving is equally good, but not as accessible. Willemstedt (the capital) is plain and simple awful. That's the only thing that put me off this island. Sadly, most big resorts are in the vicinity.
Aruba has got diving as an add-on I think, though there are pretty enough reefs, and a couple of decent wrecks, so I hear. I thought Aruba's main attraction was the Casino however. If you consider that from where you are starting in Venezuela these three islands are basically facing you, I'd plumb for the best one!
(And don't forget Venezuela's own Margerita islands...)
In Bonaire you must rent a pick-up truck, that's the whole point of being able to shore dive the entire island's sites, which are no more than a couple of fin strokes off the beach (some do have some 100 steps to climb up and down at the North end, but not too many sites are like this!). The only boat you'll need is to dive at Klein Bonaire, a small outcrop offshore which is worth the trip at least once or twice (you get prettier walls there). As advised before, if you have the new 'credit card' driving licence, you need to take the paperbased one as well. That's valid advice for pretty much anywhere I think. Watch out for the wild donkeys on the road, they are a menace.
Don't expect big pelagic action on either Bonaire or Cura?ao. The biggest thing you'll find is green moray and nocturnal tarpons. There are no sharks in-shore, and very few big jacks/jewfish. But, what macro-life!! That's got to be at the other end of the scale.
Enjoy, but it's a pricey destination. Imagine Little Holland in the sun, and you're about there for feel of the place, with price tags to match. A simple 3 course dinner with wine will cost you $30 to $50 plus per person. A self catering deal with optional days eating out seems a good idea, and certainly one which I would seek out next time. There's a great mini-mart in the centre of Kralendijk, with reasonable prices. The Dollar is cheap, for now...
Well, have fun there, wherever you end up at. I am envious.
Jeanne