This is now becoming a big adventure. Looking at total cost, there is no real price difference for us to fly in on 22nd via Iceland and rent an apartment, then to fly in on the 25th and get a hotel. Icelandic air will let you break your trip home in Iceland for no additonal fee, so it looks like a few days in Iceland after the cruise.
As for do it yourself tours, the best single euro I ever spent was for the bus from Villefranchise to Nice. We walked around, got fruit at the farmers market, went to the beach (rocky) ans swam.
This time we plan to take the same bus in the other direction and go to Monaco.
Since we have done the Vatican before (and I expect it will be a zoo since the Pope is speaking the day we are there) we plan to take the train to Rome and do other things.
We have climbed the Pisa belltower, so are skipping it and heading directly to Florence, plan to pre-buy muesum passes.
My boss is allowing me three weeks vacation, in part because she wants something from the glass factory in Venice, so that is now high on the list