We went July 2007. First we saw David and a bit of the other art at the Academy-took about an hour. Then we had a one hour walking tour of Florence with the local guide. After that, we had about 3.5 hours on our own, and this included lunch. Several folks skipped the walking tour to visit a specific sight or to do more serious shopping, but I don't remember if the Uffizi was one of them. The day in Florence is really short so you will have to decide what is most important to you, and definitely get the tickets in advance.