Tami,
When you say "I have never been there..." do you mean you haven't been to the Greek Islands / Adriatic ports or all of Europe?
IMHO, while this is a wonderful itinerary, it is an itinerary for someone who has already been to the cruise-highlights of Europe like: Rome, Florence, & Barcelona.
Just my 2 cents....food for thought.
Enjoy your planning and the trip!!
P.L.
PS: Please spend at least one night in Venice (on the island) to soak it in. Go to St, Mark's Square at night to hear the orchestras play in the outdoor cafes. Unforgettable experience!