23 day itinerary input

Sounds good, but you might want to rethink your one night stays. You're going to Verona for 1 night (I know, to return the car), then to Milan for 1 night. And you have a 1 night stay in Orvieto. That is a lot of unpacking, repacking, checking in and out of hotel, etc. It doesn't give you much time to see the sights. Most people prefer to stay 2 nights if possible.

I think you are moving around too much. Too many short stays. You say "1 night 2 days Milan" but I don't know how you can have that when you plan to arrive on the evening train... Seems like 1 night and part of one day. Not really worth it, IMHO.

I would drop the night in Milan and add another night to wherever you are staying in the Dolomites, which are magical. (Where are you staying?) Stay in the Cinque Terre 3 nights (I saw your other post where you are vacillating a bit).

Orvieto is not in Tuscany, it is in Umbria. Perhaps you can skip the night there and add it to Florence (where I don't think you have planned enough time given what you want to do), then see Orvieto for a few hours on your way to Rome.

FYI, it is easier to view an itinerary in nights than days. Four nights = 3 full days in a location.

I agree, count nights rather than days in your summary. I always start at night "0" if my flight takes off at night and arrives the next morning ("1"). Travel can take from an hour up to 9 or more hours of a day, seriously eating into sightseeing time.

I agree with the others that there are too many one night stays. Those typically only allow a few hours in the evening to tour a new destination. One night stays are a bit of a nuisance with the checking-in and out, packing, unpacking, etc.

Note that when renting cars in Italy, each driver on the rental form must have the compulsory International Driver's Permit, which is used in conjunction with your home D.L. It's easy to obtain I.D.P.'s at any AAA office for a small charge and these are valid for one year. You'll also need to be extremely vigilant to avoid the dreaded ZTL (limited traffic) zones which exist in many Italian towns, as each pass through one will result in hefty fines (do NOT drive in Florence).

If you are planning to base in Val Gardena while in the Dolomites a car is really unnecessary there is efficient local bus service. I was given a free pass at my hotel. The Dolomites are special 3 days is good but you'll want more! Easy to get there from Venice...train to Bolzano..bus to Val Gardena

I'd leave out Milan to ease things up a bit.
Get a rental car from Venice for the Dolomites (returning in Verona), then again from La Spezia (after CT) for Tuscany and Umbria.
Venice - 5 nights
Dolomites - 3 nights
Florence - 3 nights
Cinque Terre - 3 nights
Tuscany & Umbria - 5 nights
Rome - 4 nights

Thanks for all the input; it is really helpful. I have at this point the following-expressed in nights! I have Milan in the itinerary because I have always wanted to see The Last Supper-some love it, some say blah....but that's art! I hope to take a hidden gems tour in Milan as I believe most cities have much to hide. Milan is a transfer point from Venice to CT, so the stop is logical.

Venice 5 nights including the night I arrive and will be beat!
Dolomites-3 nights
Milan 2 nights
Ct-2 nights
Florence-3 nights
Umbria-Montefalco and Orvieto-4 nights (car)
Rome 4 nights

I believe The Last Supper is well worth it. Make sure you secure tickets when they go on sale 3 months out.
Your itinerary works well. Enjoy.

One other thought would be to reduce Venice to 4 nights.
Allowing for you to spend 2 nights in rural Tuscany near Siena.
Followed by 3 nights in Umbria at Montefalco.
Before returning your car in Orvieto and heading to Rome.

Indeed, I have thought about shortening Venice by one day. Still thinking on it. I want to take in some hands on activities there (daughter just turning 18) and music, so we are not solely 'site seeing' . Add in a day trip and it doesn't seem so bad.

I am concluding one has to make some choices and not look back or it all moves around with no end in site. Like most countries how to chose!