The thing about colored backgrounds, sometimes they get a bit too intrusive. Fortunately, it's very easy to adjust not only the color, but the brightness and saturation of your backdrops... without affecting the subject itself.
In my lynda.com title, Portrait Retouching with Aperture, I have the following tutorial to help you get your backgrounds just the way you want them.
More Aperture Tips and Techniques
In addition to Portrait Retouching with Aperture, you may want to check out my other Aperture titles, including Aperture 3.3 Essential Training (2012), Using iPhoto and Aperture Together, and the latest, Enhancing Product Photography with Aperture. Also, take a look at our Aperture 3 Learning Center. Tons of free content about how to get the most out of Aperture.
Aperture Workshop Coming on Nov. 16 and 17, 2013
Want to learn Aperture in a hands on environment? My next Aperture workshop will be Nov. 16 and 17 in Santa Rosa, CA. We'll review all of the basics, plus work on portraiture (including a live model shoot), product photography, and more. Write me at firstname.lastname@example.org for more information and a reservation form.