Advice Needed: How to spend 11 days in Italy?

What do you mean by " usual Rome tour" .. " usual Venice tour" ?

Your itinerary is too ambitious for 11 days only. You need to cut down some.
The best way to plan is by counting nights not days.
So count the number of nights you have on the ground in Italy, then allocate nights. Remember that 2 nights in one location = 1 full day at that location.
Since changing hotels often is a time waster (because of the logistics of checking in/out and packing/repacking) I recommend you stay at least 2 nights at each location you want to stay.

This is my take on the locations you are considering:
Dolomites: 2 nights is the absolute minimum, if you have a car. Without a car it takes longer to visit the mountains, therefore without a car I would consider a minimum of 3 nights, at the very least.

Venice: 2 nights (1 full day) minimum. If you want to include Murano/ Burano islands, then you need at least a 3rd night.

Florence: 2 nights (1 full day) is the very minimum for Florence alone (or some of it). If you want to take day trips somewhere in Tuscany (Siena, Pisa, Lucca, Chianti hills, other small hill towns) then add a night for each day trip.

Cinque Terre: Although it can be visited as a day trip from Florence, however by train it's almost 3 hour trip each way. If you want to enjoy it more, you should spend at least a night or two.

Rome: 3 nights (2 full days) is the minimum. 2 nights (one full day) is possible, but you will be able to see only a fraction of what Rome has to offer.

Sorrento and the Amalfi Coast. I would not visit there with less than 3 or 4 nights at my disposal. The logistics of getting there are time consuming and there is too much to visit in this area to spend less than 3 nights (2 full days). Actually 4 nights is the only time that would be worth it for me.

Sit back at your drawing board, and rethink your trip. You definitely don't have enough time to cover all the ground you think.

I was going to say count nights, not days but Roberto beat me toit while I was logging in. god advice from hi. Read and then cut back on your plans.

You need to factor in travel time between cities, getting to and from hotel, and checking in and checking out.

We spent 10 nights in Italy before embarking on a cruise Venice 3, Florence 2 and Rome 5. And we felt rushed. In Florence, we had 2 nights but only had one full day. Some of us stayed in Florence and crammed in the Uffizi, Duomo etc. The others did a 10 hour Tuscany tour including Siena and San Giagimano(sp). Pick one. There is no way we could have done both. You will have the same problem x 5.

Instead of adding another town, you may want to cut 1 or 2 from your itinerary.

I am not opposed to whirlwind tours, especially with a car, but traveling by train you have schedules, etc. to worry about and you will spend a ton of time getting places instead of being places. I would at least do one of the locations 3 nites, and possibly 2 of them. You also might consider doing Tuscany instead of Florence for 3 nights. Take a day trip into Florence if you like the countryside and nature more than museums and cities. With you day trips from Florence and Sorrento it sounds grueling.
By the 'usual city tour' I am assuming you mean to see the highlights that interest you in each of those locations. Correct?

Sounds like adding a day some where and plan to do nothing could help. Based on the reply above, sounds like I am allocating little time for Dolomites (1 night, 1.75 days), Florence (2 nights, 2 full days), or Sorrento (2 nights, 1.5 days).

Definitely too ambitious. I also arranged my own tour starting in Venice June 14th and am spending 3 nights in each place. I want to see the "tetrarchs" built into St Marco basilica that Rick Steves cuddles and dusts but doesn't explain. His TV programs cater to the knowledge of the average American tourist who come from the New World and don't have an adequate sense of history. I know he knows but doesn't have the time to explain. These are when the Roman Empire was divided into a tetrarchate and maintained the old pagan myth and Roman authority and then Constantine had the idea to side with Christianity and was able to rule the Empire single handedly again, until after 70 years that too didn't work, Rome is invaded by Alaric by 410 AD inspiring St Augustines City of God and then finally fizzles out in Ravenna about 80 miles from Venice. Unless you spend time there you want appreciate these historical nuances