First class upgrade
For travel on US Airways and you have travel benefits on US Airways, just list on theHub like you would a domestic ticket. At the end it will say how much taxes are. I know I just came back from Rome and it was $79 for two. Purchased upgrades to first at $100 each per leg so r/t was around $238 each in Envoy.
Also, if you want to try and go first, uhh excuse me Envoy, you will need to purchase the upgrades. They can be purchased at any ticket counter. Just go to the one where you are based before leaving on your next trip. Make sure they charge you $100 though for an international upgrade. The computer program automatically defaults to $20 for domestic upgrades. International are $100 and are refundable if you don't use them. They are also valid for travel for 1 year.
Also, when you travel, if you are riding on an A330 and you use your upgrades to get into Envoy, ask if row 1 is available. It used to be first class and the seats lie completely flat. Very nice and comfortable for trans-atlantic night flights. Envoy pax must pay extra to sit here and if it is not full, the gate agent can seat non-revs there.
For travelling through the airport on your return, it will just be like when you leave the US. Check-in at the ticket counter, tell them you are an employee. They will check your passports and issue you tickets like in the US without seat assignments. Normally, about 30-45 min before departure they will start to clear non-revs. No different than the US.
One tip though, before you leave the airport when you arrive, find out where the check-in counters are. I missed my return flight out of Rome because I got on the wrong shuttle bus. Apparently in FCO, US carriers park at terminal C but check-in at Terminal 5 which is kinda hidden away from everything. O well. One extra day in Rome. Enjoy Europe. I always have!