Personally, I find it interesting and a bit puzzling that people want to buy a sailboat to "learn" to sail on...
John, Here's my five-step process to getting into (or bailing out if it ain't your thing) of sailing:
1) Befriend a competent person with a sailboat and have him teach you. If that isn't possible, join a sailing social group. These groups match-up people who own boats with people who either wanna crew, learn to sail, or just enjoy sailing in general. If any of these don't work, enlist in a ASA certified sailing school.
2) Next (if you still think sailing is your thang), go buy a sailing dinghy. Sailing a dinghy will REALLY hone your skills, and teach you a lot about the physics of sailing.
3) Next (if you still think sailing is your thang), Join a Sailing Club. Sailing clubs allow you to rent boats by the hour, by the day, or by the weekend. Here you can start out small (foot wise), and work your way up to the size of boat you think you may eventually wanna own. If cruising is your end game, this is where I see most newbies discover that they would have quickly outgrown that 20-something footer had they bought one.
4) Next, If you've come this far, I'll assume sailing is your thang
, and the somewhat controversial portion of my advice: If you truly love sailing, and, cruising is indeed your end game, and you have the resources to do so, go buy the boat that will fit those needs, and carefully grow into it. You won't be sorry you did.
5) Go enjoy life on the water.