Italy, Switzerland, Germany, and Austria

Hi, Start by going onto a site, such as www.rome2rio.com and seeing how long it takes to go between these locations. Your two days will be more like 1 day of travel & getting checked into/out of the hotels and 1 day of enjoyment between some of these locations. You 'll end up disappointed that you didn't really see or experience anything.

Interlaken - imagine being at Disneyland but only going to the front gates! Don't stop at Interlaken; go to Murren or Wengen to really see this amazing area, and plan at least two days there (not including travel time).

My advice - select locations that are not more than 3 hours apart by train. (I aim for 3 days at locations & 2-3 hours by train.) Which of these are your real priorities? If you want to be in the mountains and also want to see Venice, then choose the Dolomites over the Swiss Mts, for instance. Personally, we really enjoy traveling by trains which are efficient, allow both of us to relax & enjoy the views. We'll grab some food from a grocery store and aim to eat lunch on the train, so we're ready to go at the next location.

Jean is right. 2 nights in one location = 1 day. You've picked some incredible places and you want wayyyyyyyy more than one day in each. I was on the BOE 21 day tour in May, so spent 2 nights each in Venice, Florence and the Cinque Terre (Montorosso) as well time in Germany and Switzerland. 2 nights in each city barely gives you a sample. To make the most of our limited time in each place we were touring from 8AM until 8PM or later. You can cram a lot of great things into those 12 hours, but you're not relaxing through any of them. Do yourself a favor and give yourself AT LEAST 3 nights (2 days) in each place- even if it means shortening your list of cities. Plan for a minimum of half a day to drive or take the bus between locations. For us by bus took 6-7 hours between cities and of course that doesn't include time to find parking if you drive (and catch a vaporetto to Venice which is an island). That doesn't include time checking in and out of hotels. Give yourself time to enjoy and savor these incredible places. With the RS tour, we had the privilege of skipping lines at iconic places and the benefit of local guides to get us to places directly at the best times. When you're exploring on your own, everything takes even longer. By the way, the drive to Cinque Terre requires a knowledgeable driver with nerves of steel as you are tackling very narrow cliff-top roads designed for one vehicle but often tackling two. I vote bus for that!

It sounds like a wonderful trip you're planning. Enjoy!
Lisa

You don't say where you're flying into Florence from. Venice and Florence are relatively small airports, and Pisa, Milan or Munich might be a better airports to get into this region.
Efficient travel is visiting cities that are in close proximity to each other and in a straight line. Your itinerary is to cities in different directions--almost in circles. Why don't you choose some different cities that are easier get to?

How about flying into Munich and taking train over to Salzburg?

Then take the train down to Innsbruck to see The Alps.

Going through the Brenner Pass by train into Northern Italy to Venice is an easy train trip.

Then take a fast train to Florence before taking the train to La Spezia and the Cinque Terre.
You can take a train to Milan and Lake Como is just 45 minutes north.

Then fly out of Milan, Italy's second largest airport.

All of the destinations on your list are served by train but they're not especially fast trains. You don't need a car and cars come with their own issues, such as parking, energy to drive and navigate, and different toll rules/stickers for each country. http://www.ricksteves.com/travel-tips/transportation

Packing light will help as you navigate both train stations and getting to hotels at each destination.

I agree with Jen Rome2rio, loco2 or goeuro.co.uk are the best way to plan and compare, the last two have booking and they help have all the trains in Europe... I think they even have an app so you can search and book as you are on the road.