Can you do the trip in reverse, into Venice and out of Milan. It probably doesn't make much difference unless you have a morning flight out of Venice - it can take a very long time to get to the airport. You could also go round-trip Milan and change your route to a loop (lakes, Dolomites, Verona-Venice-Padua-Bologna-Milan). You can continue from Milan to Como on arrival day and spend your last 1-2 nights in Milan before flying home. A car will be helpful for the Dolomites, maybe for the lakes (haven't been to any). For the rest, the train is better. You said you're flying via LHR. Are you spending time in London on this trip? If not, are you booking your flights to/from Italy on the same ticket as the ORD-LHR flights? If so, you might also consider flying in or out of Bologna. If not, be aware of the substantial risks of connections on separate tickets. LHR is notorious for long connection times.
You'll be in the Dolomites about the same time that I was (RS Alpine tour). It was lovely, lots of spring flowers. That year - 2015 - the late May RS tour had better weather than mine did. Also expect rain in the afternoons. It's usually not too long, my tour had bad luck and it poured from about 2-4 pm. It was still a wonderful day.
Verona is one of my favorites in Italy, especially in the evenings. There are a number of interesting sights (google Verona Card). I haven't been to Vincenza. I was less impressed by Padua. If you are going to take the University tour in Bologna (highly recommend it), skip the one in Padua - it isn't as good.
Ravenna is much better as an overnight - or even 2, arriving late and leaving early, so you'll have one full day there. It has a very nice historic center, just a few minutes' walk from the train station, and good restaurants too. You'll walk everywhere except to the must-see Basilica of Sant'Apollinare in Classe (take the bus or a taxi). I stayed at palazzogallettiabbiosi, loved it.
If you want specific hotel recommendations, we need to know your price range and minimum requirements.