Depends how many stops you'd be happy with. Five centres in 2 weeks would be a lot in IMHO but it depends on your own energy levels. If you're sticking with cities, then Bologna, Florence and Rome would be good stops.
Another option would be to get the train to either Siena (and spend a few days touring Tuscany by car before getting back on the train in siena and continuing south) or Naples (and spend some time around the stunning Amalfi Coast, also taking in Pompeii, before getting the train or ferry to Sicily).