In May I had an itinerary similar to yours--Rome (5 days), CT (2), Rapallo (1) Tuscany (5), Venice (4). If I could do it over I would have skipped the jam packed, tourist trampled CT and spent more time in Venice.

I can only second what everyone has said.

I have been to Venice twice in the last 4 years and spent 5 days on each occasion. The charm and joy of Venice is getting away from exactly all that you would see on your 1/2 day tour. It is the daytrippers that are ruining the city and they are the reason the city has considered charging an entry to visitors.

The joy of Venice is to walk around a silent neighborhood at night, to see children playing football in the alleyways and eat wonderful seafood at a small bar. Don't go for the day, either you'll hate the place or wish you stayed longer.

I am going to join the chorus and advise that you either skip CT or Venice but you absolutely cannot "do" Venice in 1/2 day. Whoever told you that should be ignored for all future travel advise. I personally would pick Venice over most any other city in the world. The magic of wandering the cobbled streets at night, getting lost, watching families meet in the squares in the early evening and simply enjoying a glass of wine and watching the world pass by is amazing. I wouldn't even have time to get lost in 1/2 day, which is one of the best things to do in Venice.

Have you see guidebooks or travel shows about Venice? Did you think, "Wow, I'd love to see that some day"? If what you know today about Venice hasn't convinced you enough to put it on your itinerary as a destination to truly see and experience(and NOT for a 1/2 day) then you should skip it. You should research and choose the cities that speak to your love of its art and architecture etc, and not because it's just there.

You didn't say what month you would be traveling to Italy. I think that makes a lot of difference if you want to avoid the summertime touristy Venice with it "amusement park" atmosphere.~~~long lines etc.
Having said that, it IS a beautiful,UNIQUE city : but with Rome, Tuscany, and Cinque Terre planned in the 10 days, I would save Venice for another time.(and "do it justice", as the old saying goes). It IS way on the East side of Italy.
We avoided Venice the first 3 times to Italy, never were interested.......but did include it in a driving circle down from Austria, and back through Lake Guarda etc. We got a wonderful "overview", and really liked Venice and want to return for an even longer stay (maybe some January!!!)

Give Venice at least 3 nights...My Girlfriends and I went to Italy in the Fall of 2006. Round trip from PHL to Venice. I recall asking the advice of Fodorites. "I will be in Italy 10 days we plan Venice, Florence, Rome and was looking for a 4th locale". I was told and rightly so to forget the 4th and reconsider limiting the trip to 2 places. We did and decided on Venice and Florence. 10 funfilled, food filled, Art filled and wine filled unforgettable days.