If you have mon tue and wed in Rome I think that's about right-1 day for colloseum, trevi fountain, roman forum, etc. Half day for Jewish quarter (I highly reccomend Rome for jews-really expensive but I don't see how could get so much out of it without it). Day for Vatican city.
Leave wed night for Florence. Spend day in Florence. Don't miss the shul (shul is open every other half hour) and I recommend the going to see the david. It's one of the things you can't appreciate until you see in person.
And then Thursday night to Florence.
I can't see spending more than a couple of hours in murano. Didn't get to the other islands. Also a lot of things are closed during august-just something to be aware of.