July Itinerary

This is the only thing that is not interesting:
Getting to Bolzano from Manarola takes at least 5 hours requires 2 or 3 trains

I think you are trying to do too much with a lot of travel time between locations where you are staying for only a couple of nights each. In short, for 12 nights you are planning on staying in 5 locations and criss-crossing the north of Italy. I recommend dropping either Bolzano or Venice and adding those nights to the other. That is, 4 nights in Venice or the Dolomites and I recommend the Val Gardena, east of Bolzano as a better location.

The Val Gardena will give you a respite from heat and cities. Bolzano is in a valley and is HOT so do yourselves a favor and get up into the mountains instead. Staying 4 nights makes it worth the trek. You do NOT need a car in the Val Gardena. You can take a bus (about 1H15M) or for easy travel and economical for 4 people, hire a taxi for about Euro 85.00 from Bolzano train station to Ortisei in the Val Gardena.

If you are stuck with tickets out of Venice, i.e., airline arrangements already made, you will need to spend at least one night there. So maybe another trade off would be to drop the vague part of your trip driving through hill towns and spend those two nights in Venice.

3 nights Florence

3 nights Manarola

4 nights Dolomites

2 nights Venice

My reaction was similar to Laurel's. I was going to suggest moving one night from the Cinque Terre to the Dolomites, but I agree that cutting one location would really be better.

Laurel's right about how hot it can be in Bolzano (which is a very attractive place otherwise), complicated by the fact that a lot of the Bolzano hotels don't think they need air conditioning. They are wrong. If you stay at altitude, in a village like Ortisei, you won't need a/c.

I spent a week in Bressanone and Bolzano in 2015 (yes, I'm a slow learner), and I was satisfied to use the buses and mountain lifts to access some easy walks. The tourist offices in the area can usually supply you a handy booklet with all the local transportation schedules--trains, buses, chairlifts, etc. It makes it very easy to plan your daily activities.

Edited to add: With half the segments of the low-level Cinque Terre hiking trail closed (and lots of stairs to climb to access others, if memory serves), it's easier to walk in the Dolomites than it is in the CT.

I would reverse your trip and fly into Venice because it can be difficult to depart from. You are zipping back and forth a lot. I would cut something.

Thoughts on Venice vs. Ortisei? I have been careful to select accommodations with a/c as I know my family well :). Skip Venice and fly out of Milan instead? This was my original plan, but thought I might try to squeeze in Venice even though Venice in July doesn't make the top 10 list for my traveling companions!

If you ae on the edge about Venice, skip it. The time in the mountains will be refreshing and a real change of pace.

Thanks for all the advice, truly helpful! We do not have airline tickets yet, so I am still quite flexible. I'm thinking to cut Venice as mentioned and stay in the Val Gardena. Now I am balking at public transportation from Cinque Terre to the alps. Thoughts on driving from La Spezia to Val Gardena, keeping the car there and using it to get to our departure airport (prob MIlan)? Seems to be cheaper in terms of time and money, but I am reading some horror stories about driving in Italy. We did drive just fine for 6weeks in New Zealand, although I suspect the driving culture is quite different. Appreciate the feedback!

If your path is La Spezia to Ortisei, a car is a good idea. It will be much faster than the train/bus combo given the route (see Rome2Rio.com for time comparisons). You will be fine driving in Northern Italy. Just drop the car in Venice and enjoy the last nights in a car-free environment. Do allow plenty of time even on the autostrada as summer road work can cause giant slow downs.