All airlines are about the same in my book (bad).
I just try to avoid connections in the Eastern US and try instead to fly directly from the West Coast to Europe through the Arctic route, preferably with a flight operated by a foreign carrier, even if in code share with a US airline.
There are no non stop from the West Coast to Italy, so I generally fly non stop to some other European hub to catch my flight to Italy. I think from SEA you can fly non stop to Europe to Paris CDG (Delta), AMS (Delta), FRA (Lufthansa), LHR (British Airways). I would take one of those, even if it costs a few $$ more. I'd do anything to avoid airports back East (like JFK, ORD, or EWR). My favorite European airline is Lufthansa, in part because they are affiliated with United (with which I have lots of miles) and therefore they have lots of flights out of SFO (which is a United hub), but also because they always gave me the best service.
If you fly to VCE I don't recommend British Air because they only one daily flight from London LHR to VCE.