I have often thought that Missy of Roumania would have made an excellent Russian Empress. She was bright and shrewd (though not in a calculating or unkind way) and possessed the beauty, charisma, ego, and sense of theatricality necessary to the position. Now, what if she and Nicholas had fallen in love and gotten married? Given his passivity and tendency to defer to close female authority figures (i.e. mother and wife), I imagine that Missy would have tried to "manage" him to project him as being the powerful, autocratic but benevolent ruler that Russia required. Since I don't think she could have succeeded in this task, nor do I think the Russian people would have accepted Missy as the one managing the country, I think she could have been a spectacularly successful Tsarina ONLY PROVIDED THAT she were married to somebody whose personal dynamism equalled her own.
Missy's memoirs indicate that she found Alix a bit of a drag to be around.