Maybe a double one in the middle and one to the left and one on the perpendicular wall. Eye level lighting is better that over head for the vanity. Here is an example of placement, not style:

You could try just two in the middle first and see if that is enough light:

A second option to consider is drop down lighting. There are many different sizes, shapes and colors to pick from.

There is not much room on the right side, so finding wall lights to fit will be a bit more challenging. Because that light will be so tight, you will need four to make it look right. Just two in the center will make shadows even with the recessed cans above. Pendants would not be my first choice with that style mirror, but a long skinny cylinder may look good and circumvent the tight squeeze on the right.

Thanks for the comments so far.

Here is perhaps how the lights in the middle and right might look.

http://houzz.com/photos/471421

Then the light on the left will look out of place.

Fred S - do you mean the light on the left will look out of place because it will be different (no left face wall) than the light on the far right?

here is the picture that shows all four http://houzz.com/photos/471417

Yes, that picture has both end lights on the side walls and that looks ok, but not my favorite. How wide is the wall space between your right mirror and the side wall?

From the edge of the mirror to the wall is 3.25 inches - thanks!

put a quarts light in the middle thats it.

These would fit. They are designed to use a single gang outlet box.
http://www.brownlee.com/catalog/product.php?model=5176

This is a good example of why I use the mantra "begin with the end in mind". When lighting mirrors the light should always be in front of you to light up your face and that light reflects back into the mirror for the best visual for applying makeup or shaving or what have you. This is why actors dressing rooms have the "broadway lights surrounding the mirror. Form follows function. With proper forethought the sinks could have been spaced differently and/or narrower mirrors could have been purchased so that the double center sconce with single sconces to the left and right would have worked fine. Now you must find the function that follows the form. There are many lighting choices in the market today, any one of which could be used to solve the dilemma. A good lighting design specialist would be able to point you to available products to fit the need.

Yes, that is pretty much what asoliveri is asking for.

This type may work, but might require some ingenuity.

http://www.barnlightelectric.com/wall-sconce-lighting/vintage-wall-sconces/bostwick-bath-light-bracket-hudson-valley-vintage-lighting
http://www.lightingshowplace.com/minka-lavery-ml-62-pl-brushed-nickel-contemporary-modern-single-light-energy-star-rated-mini-pendant/f347684

I agree with the designer who mentioned proper planning with the end in mind makes all the difference. My suggestion is re-purpose the two mirrors. Go with a mirror full width of the sink, maybe pick up the right hand wall as well. Mount sconces directly on the mirror (plan and measure accurately before having your mirror cut). Light in front of your face is tremendously better than lighting from top. The effect will be softer, improved lighting. Oh- and put these lights on a dimmer. The light output will double from the reflection.

I can help you. Years ago I authored "Can't Fail Color Schemes" which was a best seller for over a year. My second book is Can't Fail Color Schemes:Kitchens and Baths. It comes with over 500 photos of kitchens and bathrooms and is a priceless tool to see what the possibilities are for rooms of all shapes and sizes. I found the Barnes and Noble link but you can also check your local bookstore. I hope this helps: http://www.barnesandnoble.com/w/cant-fail-color-schemes-kitchen-bath-amywax/1110764475?ean=9781580114134

Your lighting fixture needs to be between the mirrors as you have no room on the sides to achieve even balanced lighting. That makes the lighting fixture focal & important as it occupies the center. Pick the right sconce fixture (s) that have a good uplight and more downlight component to them and place it on a dimmer. See some sconce ideas at www.railroadware.com

Could you not remove the crown molding from the top of the mirrors and mount fixtures above?

How do you move can lights to the wall? I have same issue in both baths.