Uhh... Age of Wonders? Should be fairly easy to get into for someone with Master of Magic experience, as they're quite similar. The original had very nice atmosphere and happens to contain a number of very happy memories of mine (plus, great soundtrack). The second one ironed out some gameplay issues, but AoW and AoWII shouldn't really be linked together as part of the same series, there's really no connection between them. Also, I personally think that AoWII trashed all the 'fluffy' parts that AoW nailed. It's a gimme between more balanced gameplay and more awesome setting/story.
The first Dominions can be fun for a change. The demo can be played as any race for any length of time, but with spell levels capped at 4 and some units taken out. It's neat because the simpler pixellated province display will actually change to reflect the temperature and growth scales. Also, I personally think the UI is better in Dom1 than in the succeeding titles, but this isn't a major selling point considering all the other goodies the later ones added in.
You can always play Conquest of Elysium if you want an Illwinter blast from the past, but it really doesn't grant that many choices for playstyle after you've selected a character. There are plenty of characters to pick from though, plus it's free.