Rome, Florence, Pisa, Venice in 6 days - Need tips

How can you cover all in such a short time?
Pisa can be visited from Florence, however given the short time available you should drop it.
No need for passes. Buy point to point tickets. If you buy ahead you can buy at a discount (supereconomy or economy fare). However if you pre purchase those fares on a specific train you can't make changes or get refunds. I'm not sure any of those fares are left since it's so close to the time you go.
Check on www.trenitalia.com
Station names must be spelled in Italian:
ROMA TERMINI
FIRENZE SANTA MARIA NOVELLA
VENEZIA SANTA LUCIA.

You will barely taste the Campari on your lips with the lightning speed of this trip thru Italy.
Day 1. Arrive Rome - 3 nights
Day 2. Rome
Day 3. St Peters & Vatican
Day 4. Early morning train to Florence - 1 night
Day 5. Store bags at SMN station. Visit Pisa. Return to Florence for luggage. Evening train to Venice - 2 nights
Day 6. Venice
Day 7. Fly to Paris

You've received some amazing planning advice from David and Roberto but you should also consider getting rid of some of the cities on your wish list. You simply don't have the time to do them justice. Perhaps you could just pick the two that interest you the most?

What are your travel dates?
Arriving where? Rome? Flying to Paris from??

Buy the RS Italy book as it covers all the towns you mentioned. The "must see" in each place can be from 1-7 days. On this website there is a "Rome in XX days" suggested itinerary, same with Florence. The book also has a good explanation of trains, how to take them, how to purchase tickets, the difference between a regional train and a fast train and the validations needed for each. The book will also tell you the dates sites are closed. You may find that your 1 day in Rome , what you wanted to see is closed, same with all the other places. Timing is key in planning.

I hate to be a wet blanket but to see Rome, Venice, Florence, with a side trip to Pisa you need at least 9-10 days. You can't just wrinkle your nose in Rome and instantly be in Venice or Florence. There is travel time between these places, however close they may look on a map. You'll need to get from your hotel in one location to the train station, maybe have to wait for a train, then when you arrive, get from the train station to your hotel in new location. This all takes time. With 5 full days and maybe a couple of hours on either end days, you need to limit to 2 locations or you won't really see and enjoy the places you're visiting. Remember, sometimes less is more.

Not only travel time between destinations, but being in cities takes time between points A, B, C...

Thank you so much for your responses. I will probably cut-down on places to visit.

As written, your itinerary gives you no time in Florence. Other's are right that you are trying to pack too much sightseeing into too little time. If you stick with your itinerary, just see the colosseum in Rome, the Vatican museum, the field of Miracles and leaning Tower in Pisa, and in Venice, just pick one museum or major monument; count on just this and anything else you see is extra. I let a co-worker borrow my guidebook, I am skipping Venice on my trip and I don't know what is there and I have never been to Italy. I am giving myself approximately 4-1/2 days in Florence, 1 day or less to see Pisa, 1-1/2 days to see Naples, 1 day or less to see Pompei, 4-1/2 days in Rome including part of a day to see the Vatican museum.

Your itinerary resembles a marathon at a dead run. In Italy less is more, so reduce the destinations and enjoy some leisure time. Italy will seduce you and you will want to return.

Buon viaggio,

Consider focusing on just Rome and Florence, which is the closest city to Rome and makes some sense if you need to be back in Rome to fly to Paris (you don't specify). Those two cities alone would easily take up 5-6 days and you'd still not see close to everything. But it would allow you to make a daytrip from Florence to Pisa if that really is a high priority for you. Keep in mind the city of Pisa is not all that - the main attraction is the cathedral complex (with tower). Ask yourself if the travel time and cost there and back is worth just seeing the complex.

A reasonable daytrip from Florence would be Siena. Much more to see and do than Pisa.

If Venice is a huge priority, then that could be your second city. In that case, I'd look to fly to Paris from Venice. Save Florence, Pisa and Siena for another trip (you'll want to go back).

My tip: Don't do it

Revise it to either plan below.
Rome needs more time than the others.
Although not ideal I think you could do Venice or Florence as a 2 night stay and Rome as a 3 night stay

if I had to pick towns to see in Italy as you have done, Pisa would be no where near the top 10.

Plan A:
Florence, Pisa, Venice (Pisa as a day trip from Florence only not an overnight ; this plan is better with Siena instead of Pisa and even better yet with no day trips and sticking to just Florence and Venice)

Plan B:
Florence & Rome

Plan C:
Venice & Rome