Check out
Tirerack online and use their wheel selector to get an idea of what you like/dislike in a bunch of available wheels. Also check out
SuperBuyTires for a good selection of 16 - 18 inch wheels.
If you want to get a feel for what looks good on our cars, search through the profiles on the CEG, and pan through this Wheels & Tires section for pictures of what folks have installed, there are a BUNCH of good pictures on this site for Contours with great wheel packages installed...good luck!
Technically speaking, you need to make sure the wheels in question support a 4 x 108 bolt pattern and have at least a 40mm positive offset. Just my .02!
