If you are a MP member and using SWU's I would recommend going through FRA (I think this departs FCO around 10am) and connecting to UA 901 FRA-SFO. I was just on 900 and 2 days before the flight they still had 30+ C seats available for sale/upgrade. This was during high season to Europe, so I would think that October would be even easier.

If you want to risk it, you can use SWU's at the gate for LH flights (you need to get a printed SWU in advance). Then I would fly FCO-MUC-SFO because it is the new 340-600 with flat (but tilted) bed seats and bigger TV screens. They are still working out some bugs in the system but it seems like a good product. That said I think most MP members don't like the wait and see at the gate approach for the upgrade.

You can always route through LHR (1-777/1-747 per day) but I think this just adds to the travel time.

Good luck!