rome, florence, venice

Are your tickets already purchased? If not, you could fly into Venice to start, and then end up in Rome. If you already have your tickets, you can either get an Easyjet or Alitalia flight from Rome to Venice (since you'll already be at the airport), or you can take the train, which would require going into Rome proper first. It takes 3 hrs and 45 minutes from Rome Termini to Venezia Santa Lucia by train.

Lauren, To begin with, is there any possibility of changing your tickets to open-jaw, so that you fly inbound to Venice? If not, this is the easiest solution (IMO).... When you arrive at FCO and have collected your luggage and gone through Passport control, head for the airport train station. Buy tickets for both the Leonardo Express (€14 PP) to Roma Termini as well as the Freccia high speed (300 kmH) train to Venice. I'd allow at least an hour from the time of departure of the L.E. to the time of departure of the train to Venice. The trip on the L.E. is ~32 minutes which will give you about 30 minutes to find your train once you arrive at Termini. DON'T forget to validate your L.E. ticket prior to boarding the train or you'll face a hefty fine which will be collected on the spot! The trip from Rome to Venice will be 3H:45M. Note that your destination station will be Venezia Santa Lucia (important when buying your ticket). Base fare on that trip is €80 PP. While you could save money by pre-purchase of tickets, that's a very risky propostion. If your flight to Rome is late and you miss the train you've booked, your tickets will be worthless and you'll have to buy more at full (base) fare. Tickets on the premium trains such as the Freccia have compulsory reservations, which are train, time and date specific so you MUST only board the train specified on your ticket or again, hefty fines! While you could also take a flight to Venice, by the time check-in, security, waiting times and travel from the airport is factored in, I suspect the train will be quicker in the long run. Happy travels!

EasyJet only has one flight/day from FCO to VCE and it departs at 19:45. Alitalia offers several flights throughout the day. Booked well in advance, tickets can be very cheap. What time are you scheduled to arrive at FCO?

Before you choose to fly and buy a ticket, find out what happens if you are delayed and miss the flight. If you aren't flying Alitalia into Rome, then chances are, whichever airline you choose, you will either have to buy a very expensive one-way ticket or you will buy a cheap ticket and risk missing your flight and having to take the train. Even if you are flying Alitalia and continue to Venice with them, they may not be helpful or accommodating if you miss the Venice flight since it is on a separate ticket. They may however ticket your checked bags through to Venice. STick with Ken's advice and take the train.

The train is also much more relaxing than flying. You can always get up and walk around a bit, if you want to stretch.

As suggested, you should fly with open jaw ticket. Arrive to VCE and come back to the US from FCO. Since you live in the Bay Area, you have several options from SFO directly to European hub and from there to VCE. British Airways is not a good one, since they only have one daily flight to VCE from Heathrow. The good ones with non stop from SFO to Europe (and with service to both VCE and FCO) are: Lufthansa/United (via FRA or MUC) Swiss (via ZRH) KLM (via AMS)
AirFrance (via CDG)