Hi Shannon -
I'm not surprised that you're seeing all sorts of different responses to your question as we all have our favorites in Italy for all sorts of different reasons! There's no "wrong" answer except for any of our own personal interests not matching your own. At first glance I thought your itinerary looked just fine but I'm an art-lover who couldn't get enough of Florence in 5 days, and Rome is one of my very favorite cities for history, architecture, art and, well, I can't think of a reason NOT to like it. Florence is also excellently situated for any number of very nice day trips to smaller towns.
So, the only change I might make is choosing Sorrento instead of Naples - with the understanding that it's not the Amalfi coast (neither is Naples): it's the Sorrentine Peninsula/Coast. It provides some lovely views across the Bay of Naples, though, and unless the sea is very rough, ferries/jet boats may be easily hopped to Amalfi and Positano.
Transportation to Pompeii and archeological museum in Naples by train is very easy from Sorrento as well, and it's clean and very safe - although it can also be very busy. The C.T. will be busy as well but if you're up to climbing some steep hills to churches and cemeteries in the upper reaches of the villages it's not too difficult to leave the worst of the masses behind. Early mornings are also an excellent time to get out and about before a lot of tourists are out of bed.
We found the same to be true in Capri. The farther away you can get from the piazza in Capri and the earlier you can get up to Anacapri for a wander about town, the thinner the crowds. You'll also enjoy some scenery and glimpses at pretty local residences, little shrines, some very old ruins and whatnot that many people don't venture far enough to.