Paris is pretty sweet - just, for the love of God, don't fucking drive. The metro and easy access to long distance trains make it a pretty frequent stop for me.
Years ago Paris was great fun to drive around. Getting on and off the Périph can be hair raising but when you make it, the sense of elation makes you feel so alive!
Driving in Paris is crazy as hell, and I did drive a lot in European cities. Although the worst I've ever been to has to be Bucharest. People drive hyper-crazy in Romania.
Stay overnight next time! The town surrounding the citadel is actually really pleasant and one of the staples of cuisine local to that area is Cassoulet!