Welcome to FT!

As you can see, it varies considerably between airlines. (I'm somewhat surprised at how many people aren't familiar with how other airlines do this--you'd think FlyerTalkers would be general experts on everything...or at least have done research so they know which upgrade style--with instruments or complimentary free-for-all--will work best for them! )

Since it's so vastly different between carriers, I'd reiterate the suggestion to look in the individual forums of each airline and ask clarifying questions there.

BTW, add AS to the list of those offering complimentary upgrades.

Also, a hint: if you edit your profile to add your current location, fellow FTers can help you choose a program better, since different carriers are stronger in different parts of the country. If you're already a program member (and/or an elite of a particular program), posting that can help us know how best to recommend things to you.