Three week Italy adventure

Personally, I enjoyed Milan - it is a working city and not as picturesque as Florence or Venice. However, I would caution you about taking an "early train" from Lake Como to Milan with a 10:30am flight - if the train is delayed for any reason, you definitely could miss your flight - and train delays in Italy are "ahem" not unheard of!
While the temptation is to see as much as you can, I think for three weeks this a very ambitious itinerary - remember, each change of location will take anywhere from 1/2 to 3/4 of a day between checking out of your hotel, getting to the train station, the train ride, finding your new hotel and checking in, etc - which will seriously reduce the time you have to see all these places! Also, you are doing a lot of backtracking. If you do decide to fit all this in and since you don't seem keen on Milan Milan, fly into Venice and work your way down, flying home out of Naples.

Thank you for the great advice. I think I am going back to my original plan of Varenna for 2 nights and Milan for 2 nights. You are so right about skipping Milan and catching a very very early train from Varenna to catch a 10:20am departing plane. Many bad things could happen. I also appreciate the advice about better planning to avoid travel times. I originally planned to follow the Rick Steves outline for his 17 day Italy trip, but forgot that he has a bus which makes transportation a lot easier. Also flying for us out of Spokane to Rome and returning from Milan is a lot easier and less expensive that the into Naples out of Venice idea. I do wish I had put more thought into it, but cannot change now. Anyway your feedback was much appreciated.

If your MIlan stop is for The Last Supper get your tickets right away as they sell out quickly.

I agree with Nancy, and Venice is an outlier geographically, so perhaps add a 2nd night in Assisi. All locations are wonderful, but try to limit your geography (voice of experience)--either Venice or CT. It takes much longer to get around in Italy than you think it will. Sorry to add a destination, but after Florence on the way to Cinque Terre, consider stopping for a night in Lucca--drop your luggage, go rent bikes, and ride around the walls. Also, don't cut Florence short--3 nights there is barely enough. Milan is better than you think. The roof of the duomo and two museums--the Ambrosiana and Brera--are outstanding. Since you'll be leaving from Milan anyway, Varenna is closeby and you can do some hiking there as well as the not-to-be-missed Villa Balbianello and other sites. As Rick says, assume you'll go back--we've gotten hooked on Italy and have gone 10 times now, but in small area bites!

I'm assuming that this is your first trip to Italy; and, in the absence of any information about your interests, I'll add these comments.

Rome three nights: That gives you two days in one of the greatest cities in the world. You won't even scratch the surface.
Orvieto two nights: That gives you, at best, a day and a half. You can easily fill that time there. Skip Civita. It is a great mystery to me why RS has taken to hyping Civita. It is a tiny hamlet, of no particular interest except that it is located on a hill that is being eroded away.

Florence three nights: There's too much to see in such a short amount of time and get to Siena as well. I'd add a night and/or bag Siena.
Cinque Terre: Another super-hype by RS and, consequently crowded beyond belief with North Americans. You already are including the Amalfi Coast, which, in my opinion, is much more beautiful and more interesting than the CT. Anything you might want to do in the CT, - - beach, hiking,etc.- - you can do during your four nights in Sorrento. I can't see why anyone would include the CT on their first visit to Italy. The three days can be redistributed to give you a better time in several of your other choices.
Lakes and/or Dolomites: If you were to eliminate the CT from your itinerary, you could add some time here. I'd do one or the other, not try to do both.
Milan: I agree that you should spend your last night there in order to be close to the airport. Again, it's a place nowhere near as attractive as several of the others on your list. Maybe getting there from either of the two above, and devoting however much of the day remains to what you want to see would be enough.
I think you'll love Italy - - but more if you slow down a bit and savor it than if you rush around trying to get to everything.

Thank you for all the feedback. This is our second trip to Italy, the first being 12 days in part of a 21 day adventure in Europe. I think I do get influenced by Rick Steves because in all of his recommendations he only stays a short time. To respond to some of your advice we are staying 4 nights in Sorrento in order to tour other areas, The Amalfi Coast, Pompei, and Capri. In Orvieto we may or may not go to Civita, although my wife is quite excited about it. In our stay in Florence we are not going to Siena as we were there 3 days on our first trip and bussed to Florence and realize we missed so much. We have visited Cinque Terre before but last time we were so frustrated by only having one full day there so added an extra day. As far as Venice is concerned we realize that it is quite a ways to travel, but just wanted to visit again. Our trip ends with a 2night stay in Varenna and 2 nights in Milan before we fly home. I appreciate so much your responses. We are becoming very aware that we are attempting to fit too much into our three weeks, but since we do not travel to Europe very often, this is our second time, we want to see as much as possible. Also we are older, but not much wiser. Thanks again.

You mentioned Verona, and no one seems to have picked up on it. It is one of my favorite places in Italy and fits nicely between Venice and Milan. There is certainly enough to fill up 1.5 days sightseeing, and you can even go to the opera at the wonderful Arena. If you do choose Verona, book rooms early, since they fill up during the opera season.

Personally I think you are cramming a lot considering you seem to be relying on trains and buses.
I generally prefer flying out of Rome, instead of Milan, just because Malpensa is far from the city and flights to North America are in the morning. Rome's airport is just 30 min. from the city center. But if you have your flights set, then ok.
Your trip looks good. But I would drop the Cinque Terre nights and add them somewhere else. CT are out of the way in your itinerary. I wouldn't drop Venice if you have never been.
If you do the Dolomites I would do Lake Garda and Verona instead of Varenna. Both are close to Venice.
I would also spend only one night in Milan, basically get there the morning of the day before my flight out. That should give us an entire afternoon to see what it's essential to see in Milan.