Driving trip around Poland?

Driving to Venice in a car does not create inconvenience. You just don't use it while you're there.
But a car in Rome--don't even think about it (see answer to your other post).

It sounds like and awful lot of driving in a relatively short period of time to me. Have you considered using the car in Poland and then taking the train for the Italy portion of your trip.? In Venice, you will have to park the car outside of Venice proper, pay for parking and take either a bus or train into Venice. In Rome, well let's just say, I wouldn't go anywhere near Rome with a car! You will more than likely park it for the entire time you are there. If you do decide to keep the car, be sure to check with your rental agency about taking the car out of Poland. There is often a charge for taking a car out of the country from which it is rented.

If you haven't booked plane tickets yet, I'd do what's called an open jaw ticket where you fly into Poland get from Poland to Italy on your own (train, low cost airline, etc. though noting that the drop off charges involving a rental car and a different country drop are normally v. high) and then fly out of Italy at the end. Generally not much of a price difference between an open jaw and round trip unless you hit some sort of airport tax or airline promotional fares weirdness and usually far cheaper than doing two one way tickets.

When searching for fares, there's usually a 'multi-city' or 'advanced search' option that will let you price that out.

Thank you for your replies! I am so glad I asked. :) We are flying in and out of Warsaw because we have families there and they also want to come alone on the trip to Italy. My husband still wants to drive, so we are now considering cutting Rome out of our itinerary. Now the question is if we should still go do to Pisa if we don't plan to go to Rome. The revised rough routes can be either:
Warsaw - Prague - Salzburg - Venice - Vienna - Krakow - Warsaw
or
Warsaw - Prague - Salzburg - Venice - Pisa - Vienna - Krakow - Warsaw
My thought is that we should leave Pisa for when we do eventually visit Rome and/or Florence.

Another destination we are debating is Neuschwanstein Castle. It's 2.5 hours from Salzburg and will give us an opportunity to drive through northern Italy. But it definitely makes the travel from Salzburg to Venice longer and addition will mean we have one day less elsewhere.

One thing to mention is that after Vienna our Polish families might leave us to go back to Warsaw directly, so as long as we spend the 10th night in Vienna they'll be fine with the schedule.

No, I would not include Pisa. Plenty of other Italian towns of interest are right on the main driving route, such as Padua, Vicenza, Verona, or Bolzano; or head deeper into the Dolomite mountains through smaller roads and towns. To help plan driving routes and times, see www.viamichelin.com.

First of all driving in Poland is easy. It's really like driving in the US, especially with Warsaw being one of the most American-like cities in Europe. Once you leave Warsaw behind it gets quite boring so, especially since the freeway network isn't really a network. There are many areas where what looks like an interstate is actually just a highway, sometimes with only 1 lane and if you happen to be behind a truck it can take a while.

Krakow via Wroclaw and Dresden to Prague is a very easy, all freeway (toll road) drive with plenty to see. Prague to Vienna or Prague to Nuremberg is also very easy to drive (toll). Once you're in Germany, Austria or Italy what looks like an Interstate on the map also feels like one in reality.

So what I'm saying is that from and two Warsaw you will lose one full day per direction driving through the prairie.