Thank you both for the detailed responses. We have nothing to do from our 7:15am arrival into FCO until a 2:40pm train to Florence. Our plan is to store our bags near Termini and take a private tour of Rome in one of those antique Fiat 500s. The only problem is there is no trunk space at all, so we need to store the bags. I'm now figuring 9:30-12:30 tour and then lunch before we head back to the station to retrieve the bags and catch our train.