How to bend a rectangle along a path?

I am trying to draw a diagram similar to this:

As you can see, a curvy closed shape has been drawn as a line/path. Then, part of this path (for instance by adding anchor points and cutting at them) has been selected, and a long rectangle has been bent to follow that path.

Since I will be fiddling with such diagrams a lot, I want it to be easy to:

• Resize the diagram


• Have more than one rectangle (or possible other long shape) on different parts of the same curve


• Fill the rectangle using standard fill tools


• Color and style curve


• Color and style the outline of the rectangle


• Add text to the inside of the rectangle that follows the bend.


• Easily alter the shape of the rectangle by adjusting the path that it's made to follow

I don't particularly care if the rectangle is first created and then bent, or if the line segment is somehow "widened" to turn it into a rectangle (ie. an object with an outline and a fill).

It would be nice if I had some freedom with the shape, such as using a very long hexagon or a rectangle with rounded or triangle tips (so that it looks like a long sausage) but I can live without it if it's very difficult.

How can I do this? I have Illustrator CS5.