If I have a 5-year reenlistment with 3 years being an Italy assignment, will I have a say in where I want to PCS for the last 2 years?

Probably not. It just comes down to, whether or not you will be in your reenlistment window when it's time for you to be placed on assignment. Your DEROS is three years after you arrive. You will probably be placed on assignment around 9 months before then. If you like Italy you can request an FSTE to push your DEROS to the right one or two years and then you can probably reenlist for a duty station of choice

If you want to stay on status and in Europe you could request a PCS to 10th Group in Stuttgart after your Italy tour.

Probably CONUS