Basically what BigD said. What's needed just a good variety in motivation, and also ability to do what's required to get there.

Now I'm not an authority on the subject, but I feel that there is pretty good variation in game of thrones. There are several womens in positions of reasonably great power, I don't think any of them are in it to "get the guy". If a guy's involved, it's usually just a means to get to their goals.