the queue to visit the Vatican Museums was over 1 kilometer long and honestly I didn't have the patience to stand in line for more than 2 hours (it was too long).
This happened to me when I tried to see inside Duomo di Milano. I thought it was better to see something else rather than wait for a long queue. You have visited some amazing cities, I saw Venice, Pisa, Milan, Lake Como, and Genoa. My next target is rome side and florance... I personally enjoyed my time at Genoa though...
I have to admit that I am not very comfortable wasting my time in line.
But when I want to see a place I've been dreaming about for a long time, I sometimes make an exception.
I wish that your wish to visit Rome and Florence will come true.