My pleasure, have a great time, and (ahem) don't forget to post digital photos of any GGG stuff you encounter. ;')
some sidebars:
I've heard that the Sistine Chapel is closed on Mondays (must be they have to dust).
Michelangelo's "Doni tondo" (The Holy Family with the infant St. John the Baptist) can be seen at the Uffizi in Florence, and may be a good prelude to seeing the ceiling (if you are going to do that).
Luna, Italy:
http://archaeology.about.com/od/lterms/g/luna.htm
"in Gubbio, Italy, Dr. Walter L. Alvarez discovered a thin clay layer with an unusually high concentration of iridium. This layer was found at the Cretaceous-Tertiary (K-T) Boundary."