Where are you flying from?

A couple of notes and questions...

Are you thinking of burning both the AS and the Amex points for the trip? If so you'll need to find an airline that partners with both (unless you want to travel separately.) There are only a few - Delta, Air France/KLM, and British Airways. Virgin Atlantic (symbol VS) is not an Alaska partner, and American is not an Amex partner (in the sense of allowing conversion of Amex miles to AA.)

As mentioned above, most of the airlines on your list don't offer true international first class - VS' "upper" class is basically business class, Delta doesn't have FC, and Air France only on a few routes. American has FC only on flights to London and Frankfurt (occasionally one or two other European cities, but not consistently) but not to either of their Italian destinations (Rome and Milan.)

Regardless of your destination, chances are that you'd only get to a port of entry (London, Paris etc.) in first class, then would have to go down to business class (or below) for the intra-Europe part of your travel. Whether the transatlantic portion in F is sufficient grounds to spend the extra miles (i.e. the difference between business class and first) is your call. That's why the question of starting point becomes more relevant - from the US east coast to western Europe, the overnight flight over the pond seems to many to be too short to justify the extra miles; however if you're coming from the west coast it isn't.

One other note is that with Alaska miles you're limited to Alaska plus ONE other carrier. That means, for example, if you use AS miles to fly AA first class to London you can't use British Airways to fly to Italy; you'd have to do that leg on your own nickel.

The airline that would probably fit the bill the best - good FC product, eligible for AS redemptions as well as Amex conversions, through service to Italy - would be BA. Note BA requires more AS miles than the others for first/business class redemptions, plus BA whacks AS mileage redeemers with major fuel surcharges. If you're short with either AS or Amex miles you can buy some miles from either party (usually 2-3c per mile) to "top up" your accounts.

Then, of course, you need to find availability for your dates. Usually not a big issue with first class, but date- and route-dependent.

Happy planning!