When I think about integrated design Civil 3D is far from what I think of. Autodesk appears to be focused on the bright shiny things which they think will sell seats rather then integrating the design tasks a civil engineer needs to design. It's refreshing to see a company approach a product through an integrated approach with the AutoTrack product. Here's a video of one of the features of the program, roundabout design.
Did you watch the video? Did you notice the striping changes with the grip changes? Did you notice the signs move and point towards the correct location? An integrated approach to design, where most of the linework to create a roundabout is created as you design. It is then directly linked to a corridor to build a surface. What's great is that you can modify the linework outside of the corridor, this way you don't have to wait for the corridor to get built to see the changes that will occur.
AutoTrack also includes features for turning analysis, rail, airports, and rail. The product works with AutoCAD, Civil 3D, Bentley products, and Briscad. I currently do not do much work projects of the size necessary for this tool, but if I did I'd definitely look at using this product to make me more efficient. http://www.savoycomputing.com/