Eurotrip to the South

Hi everyone, we are two couples who are planning on a ~20 days trip to the South of Europe (first of two r maybe three trips). We are sharing the time between the 8th - 28th of September, and we'll have some 3-4 extra days to stay a bit longer.

So far, the itinerary we've think of, looks like this:

Sep 8-11 = Barcelona


Sep 12-13 = Nice


Sep 14-15 = Cinque-Terre

Sep 16-20 = Rome

Sep 21-23 = Venice


Sep 24-26 = Mykonos


Sep 26-28 = Santorini

Sep 29- Oct 2 = Any suggestions??

At the beginning, we were considering to spend some time in Tuscany (Florence, Sienna, Chianti), but realized we are not to much into museums and wineries, so we took that time to include Greece.

Now our concerns are:

1. Are these the best way to transport between these cities?

2. We we are planning to rent a car to travel Italy, is it better than train for visiting these cities? Are Canadian driving licenses accepted?

3. For people who have done this, or a similar trip, what would you add or take from this itinerary?

Any suggestions for our last days (Sep 29-Oct 2)?

Thanks, we appreciate any help provided.