Le Havre is ok if you are just stopping for fuel and customs. Deauville whilst much more expensive, is much more scenic and has a good restaurant in the terminal and the town and even better Honfleur on its doorstep (well a 30 € ride away). As a town Caen has little to offer it is mainly concrete having been comprehensively destroyed during WW2. Of all the Northern airports my preference for fuel and customs is Calais, cheap, quick and efficient and if the restaurant is open you can fuel yourselves as well!