There are 2 ways a female manager with a heel wrestler can work:
1) they need to be so on devious and on the same page and both have characters you don't like but yet they seem to love each other it makes you sick. Edge an Lita is a good example of this. They pissed you off by liking each other and garnered heat by being a very good team.
2) the heel wrestler needs to use and abuse his female manager. in this type of angle, you should feel a little sympathetic towards the female in that "she doesn't deserve it" and the wrestler gains heat by treating the female poorly. Macho Man with Elizabeth is a good example of this as he was overprotective and degrading to her on many occasions.
Going with these 2 theories, let's look at which wrestlers could benefit from each.
1) in these scenarios, you are looking for wrestlers with a power hungry mentality. These type are one dimensional, all about the title type characters. Their goal is to be the best and having a woman would help keep them there. Right now, the character that best fits this mold is William Regal. His smug, "i'm classier than you" persona would pair well with an upper class female. I can't suggest a current diva for this, but take any woman you dont know about and debut her with an affluent upbringing and it might work. It would especially work if she is motivated to "keep the title classy" for her man and eventually herself. Another scenario where this is somewhat already in effect is the Hart Dynasty. Though it's tough to tell, their on screen personality is arrogance due to "better training" by being in the Hart family. Having a female that has the same background only adds to the claim they should probably make more often that "no one is technically better than us, no one around could survive the dungeon". If this group breaks up, off screen couple Natalya and Tyson Kidd could stay together and become a midcard/female power couple as they would love each other but you would hate them.
2) This other scenario requires a cocky character who sees himself above everyone, including his woman. The woman would be a subservient, a personality willing to do whatever it takes to please the man no matter how badly he treats her. Miz and Ryder seem to fit this mold very well. It would be interesting if Ryder debuted a "long island bimbo" as his valet. As a Long Islander myself, I could imagine a stupid, jappy type personality girl with low self esteem hanging around a Ryder type. It happens in real life, it could happen onscreen. This girl would be kind of dumb and at first you might dislike her, but if Ryder consistently treats her like crap, you'd start to have sympathy for her and thus dislike Ryder more for his treatment for her. Miz as well could use someone like this. The Maryse story would have stalled despite their off screen relationship because Miz is awesome in his own eyes and wouldnt' deal with a woman who has credentials. A starfucker, LA type would work well as his character is a hollywood type as a former reality star. She could want to be with him for the fame of being a star's girlfriend, but quickly turn into a victim as the Miz's mic skills would tear her a new one every time something went wrong.
Of course, having a manager is a fading idea, but it is a good way to get heat and it has worked before. These are some ideas I think that could work. There were some good ideas presented earlier in the thread, so I added some of my own. Good idea and we'll see if it is ever utilized.