Hello "Italy"

Wanted to get some input for a "tour of Italy"

My daughter (2yrs 9mths), wife and I live in Zug, Switzerland. We will host my mother in law and brother in law for 3 weeks now at the end of June, beginning of July and wanted to show them a "good time".

They would like to go to Rome, and as a result, we decided to possibly do a "road trip" from Zug to Rome with several stopovers driving our own car, rather than flying or taking the train. It will probably be cheaper, and give us more flexibility all around. Is that correct to assume?

Initially, without much thoughts or knowledge, we were thinking:

Zug to Milan, spend a night or two there get to know around;
Milan to Firenze or Pisa, spend a night or two get to know around;
Firenze or Pisa to Rome spend a two or three nights there get to know around;
Rome to Venice - spend a night or two there...;
Venice to Como - spend a night;
Como to Zug.

Are those "good city pairs" to go to? is this the best way to route such trip? what other suggestions are better with maximum of 3-4 hours driving each leg? Is it safe to assume we can "just go" and find hotels on the fly without making previous reservations? (is end june/beg. july very busy season too?)

Well, all in all, again, we're flexible, and want to have something to please everyone: the mother in law (82yrs), the baby (almost 3), and the other 3 adults...

Thanks in advance for any pointers, suggestions.

Last but not least, should I buy the tollpass so we dont have to stop at toll booths?

Another last but not least: we can also go or come back via France or Austria and see some cities along the way if makes sense.. (again, all very open at this point...)