Advice on Itinerary

Here is a nice place in Vernazza that we use:

http://www.elisabettacarro.it/

Your time is short. Two night really means about one day. Your are making four site changes not counting the arrival in Milan. Anytime you change location you lose a half day at least if not more in productive time - packing, unpacking, checking in and out of hotels, finding hotels, finding train stations and trains, getting oriented to new location - etc., etc. With a short trip you have at least two full days or a bit more of lost time. About 25% of your total time. I would drop Venice because you are back tracking from one side of Italy to the other. Save it for another trip. Add a night to Vernazza and Florence and come home from Florence.

Agree with Frank that you moving around too much for the number of nights you have. Even adding one or two nights is still not enough time. With your above itinerary you have .5 days in Milan and 1.5 days in the other towns, allowing for your day trip from Siena. If you only want to see things it may be ok, but if you want to get the feel of the towns you need at least 3 nights for each town. It's true that people travel differently but you may feel so rushed trying to check into your hotel on your arrival in Milan, check out, get to the train or bus station with enough time to spare, getting to your new hotel, checking in, rushing out to see things, repeat, repeat, repeat, that you won't enjoy or appreciate anything you're seeing or doing. Agree that you should cut out one location. Have fun refining your plans.

the main thing I've found planning my first Italy trip (30 days)is the time discrepancy between checking out of one place and check in the next one. Usually checkout is by 10-11 and checkin is 3 or later. If you're in a hotel, not so bad, since you could probably arrange for storing your suitcase; or at the train station if storage is available.

If you are at a b & b or apartment, not so much, so if you could plan for luggage storage somewhere, you could possibly add 3 hours or more to your sightseeing time.

If you won't have a car, note that bus service from Siena to Montepulciano is limited, about 6 per day by Tiemme, with just 2 of those departures in the morning; see also www.sienamobilita.it but reconfirm at the Siena train station/bus stop.

Your travel times by train will be approx ...
Milan - CT 3.5 hrs
CT - Siena 4 hrs
Siena - Florence 1.5 hrs
Florence - Venice 2 hrs
I don't see a problem with the ambition of your plan. Sure more time would be great but it's still do-able. Except for Milan, you have 2 night stays, which gives you a full day in each place. Cram as much in as you feel you can to make the most of that day. On your travel days aim to arrive at your next destination about 6pm. So store your bags at checkout and utilise the full morning before you have to make your way to the station. Consider a lunch stop in Pisa between CT and Siena.

Thank you so much for your advice, everyone! Seems like we need to cut down our destinations. I appreciate the guidance!

I agree that you've got too many places, too many trains. I'd shave off a night in Siena and add it to Florence. If this is your first trip to the Mediterranean side of Italy, I'd possibly omit Venice because it's on the other coast and more importantly, you really want more than 2 nights in Venice.