What a great thread? After having been off the boards for a while, and recently being on a LOT for a less than pleasant experience, I am pleased to share the following.
As some have posted, you can't push, or it just wont happen. In 2003 on my honeymoon, trying a discover / resort scuba class, my wife found the whole experience to be horrible. Fast forward 7 years, it wasn't until I was in Cozumel (participating in the Ultimate Diver Challenge, another tale for another time). My wife decided it was time to try again. Being she doesn't like cold, for her to be able to walk into the water, no wet suit and not be cold, helped a LOT.
I did a resort class for her, and took her on a couple of shore dives and a boat dive. The combination of the comfortable conditions and seeing "turtle" just hooked her. Now being of her own motivation, when we got back home she looked into getting certified.
If she was going to get certified, I did insist on a particular path. She is analytical and competitive, and I was confident the GUE Rec 1 path would be for her and so she went.
Even in Cozumel, I had her in a BP / W and so she knew nothing else. From day one, she now has the traditional DIR* configuration with a small steel back plate.
She loves her set up and can't imagine using anything else. So making the change may be a difficult transition, but as another member posted, I would rather dive with my wife than not. I am just happy to say, she is a DIR* diver.
(* I am not saying one method is better than another, just different)