@Ken-- I went on this trip about 3 years ago, and I noticed that a few of the optionals are different now. We did the Versailles one and the Giverny one......do not miss these!! Wonderful!!
I noticed that there is a Nouvelle Eve something in Montmarte. This is different from the one offered to us. We went on a Moulin Rouge one, which included dinner and a show. It was quite expensive (more than the Nouvelle one), and even though it was fun to experience the great show at the famed Moulin Rouge, the dinner was quite bad and chintzy. My guess is that GC got enough complaints about it (the dinner part) that they changed to this new one.
The other optionals listed are not ones that were available to us, so I can't tell you about them. It has been my experience on all 5 GC/OAT trips that I have taken that the optionals nearly always are good and enrich your trip. How often will you be back to a certain area again?? :)