I tend to agree with the others. I’m not sure trying to fit in all the “best rides” (for example) would be a way to convert him from skeptic to fan. In fact, it could backfire. If he goes thinking Disney is “about the rides”, he may come away disappointed if he’s familiar with traditional amusement park rides. Even the best coaster at Disney can’t hold a candle to even some of the milder coasters at an amusement park, for example.
So, really, it is what makes Disney DIFFERENT. I think @TheSafetyLady is spot-on about focusing more on overall experience than rides.
(Now, I recognize you didn’t specifically say “rides”, but asked for “must-do items”, so just consider this an admonition about focusing too heavily on rides IF that was in your mind.)
I also do wonder if trying to fit in 4 parks in two days is a problem as well.
If this guy really is going to be your husband (and, I guess this trip will be the final determiner if “things will work out”? ), then what you really should do is show him why YOU LOVE Disney, rather than an attempt to turn him into a Disney fan outright. In the end, he might not agree, but he should enjoy seeing you being happy there, which will likely be infectious. Who doesn’t like watching their significant other happy?
ETA: So…my final thought (uh, for now) is to pick YOUR two favorite parks, and then try to hit the highlights that you enjoy most, including rides, shows, food, and even down time.