McHellfire: We were there in September 2002 and it was absolutly grand. One warning though -- September is a big convention and tour month. As early as May, I had problems getting hotel reservations for a long stay (17 days)in Sept. No doubt May is mighty but September is satisfying.
Wish I were going again. We fell in love with Paris.

I vote for September. The weather is pretty nice. We went in October and a few days we had 70 degree weather. May is still a bit cool.