Originally Posted by fastflyer

This is a great list.

I would note that SWUs are valid from Business to First as well as from Coach to Business.

Also, there are paper upgrade coupons that behave similarly to item 2, the domestic mileage upgrades. For example, the BXP1 certificates. There are a few peculiarities: BXP1s are valid on all fares except QSON (so G is the cheapest applicable fare). Each certificate is valid for one segment.

I always keep a few BXP1s in my briefcase for domestic long-haul segments, because A inventory is often available when the list for X is quite long.