We plan on getting the Chicco Keyfit 30 car seats. Does not have to be this color but it's what we are currently registered for because I had registered for the stroller to go with it. They match, it's an OCD thing I can easily get over.
Chicco Car Seat:
http://www.toysrus.com/product/index.jsp?productId=19273856&cp=&parentPage=search

Chicco Stroller:
http://www.toysrus.com/product/index.jsp?productId=19273796&cp=&parentPage=search

I am considering the Contours as they have several different seating arrangements. I've heard that with twins you will end up going with a side by side because they hate being in a tandem seat. We may get a side by side double umbrella stroller or two umbrella strollers clipped together later but right now the tandem style seems like it would be easier for me.

Contours Options LT:
http://www.toysrus.com/product/index.jsp?productId=18867586&cp=&parentPage=search

Contours Optima Tandem:
http://www.toysrus.com/product/index.jsp?productId=11268795&prodFindSrc=search&cp=