Shari - that's a hard question. We've been a couple of times on the Millenium and loved the ship (especially our aft balcony cabin) - although our biggest complaint with Celebrity for this itinerary was that the buffet closed after normal dinner hours and at many of the ports you only got back to the ship late in the evening - exhausted!!! It would have been great to have had a 24 hour buffet, which would have given one time to shower, rest and then go to dinner. Dinner was always a ruch and we never got to see any of the evening shows..... we were always too pooped!!!!
With regards to the ports our favorites were Santorini and Mykonos ..... loved the Greek Isles!!! We also loved Venice and Barcelona. Actually Tony's faves are Barcelona and Santorini. The second time we did Livorno (Florence) we did a private driver to Tuscany and it was out of this world!! Hope this helps.