Colleen -- I'm moving this to the baking board, where we have many, many more people who can answer your question in a flash.

In the meantime, though, you might have a look at
this part of Baking911, in which chocolate chip cookies are discussed in depth.
(I have no connection to that website, but did work on Sarah Phillips's book, so I know she talks about the flat versus puffy versus chewy issue.)