Florence to Venice

Florence to Venice is a shade over 2 hours via train, so you can easily do a day trip. I will offer another suggestion - Rather than head to Florence when you land in Rome, take the train all the way to Venice and spend the night. The train from Fiumicino Airport to Venice is around 4 1/2 hours. This way, you can experience Venice at night as well as most of the next day. You can see train schedules here
http://www.trenitalia.com/tcom-en

and here

http://www.italotreno.it/en

Is your work commitment in Florence or Venice?
I find that a day less the travel time for Venice is so few. Why don't you save this also for your next trip?

Are your work commitments in Florence? You could actually go to Venice after and spend one or two nights in Venice too.
These could be your itinerary (in parentheses where you spend that night):
Arrive Rome and go straight to Florence:
Monday (Florence)
Tuesday (Florence)
Wednesday (Florence)-work
Thursday (Florence)-work

On Friday you could go to Venice for two nights or stay an extra day in Florence and go to Venice on Saturday for one night. That depends on how much you need to see in Florence/Venice and how much time your work takes on the days you have to work in Florence. Maybe you can squeeze some Florence sightseeing in those evenings. The Uffizi are open till late night some days.
Friday (Venice or one more night Florence)
Saturday (Venice)
Sunday (Rome)
Monday (Rome)
Tuesday (Rome)
Wednesday (Rome)
Thursday (back at home)

I'm doing a day trip to Venice from Florence in April. I won't see everything but I figure I can the next time I visit. I couldn't pass up the chance to spend a day in Venice.

I'm with Stephen. Go straight to Venice, get a hotel by Santa Lucia station, experience Venice at night, next evening take the train to Florence.

Thank you for your responses, everyone!