Re: captains license
Some of the classes provide very good classroom instruction but it is just that, classroom stuff not out in the real world. When I originally got my license, I took a class through Boatwise and had the owner Rick Kilborn as the teacher. He did a very nice job and was a good teacher. Having several of my friends in the class really helped too and we were able to study together which was great. I have had other friends take classes through other schools which they were less pleased with.
As stated above, captain's license classes teach to a specific test, some more so than others. The test that they are teaching to is really setup for people looking to run power driven commercial boats so it gets heavily into regulations and other things that are not essential for recreational boaters. The test has no practical exam and many people feel that it is actually a poor test for commercial captains. Even the practical sections such as navigation are in a way impractical as they give you so much time. If you took as long to do the navigation problems as they give you on the exam, you would have long since been off course and run up on the beach. You will find very few mentions of sailboats and learn very little about actually how to handle the boat.
As recommended by others, something like an ASA course would probably be best. Ideally, you would have a large practical component on the water with a little bit of classroom instruction to cover the stuff like lighting configurations.