Originally Posted by dstan

• How do I book an upgradeable fare?

All published fares are eligible for 500-mile / sticker and EXP upgrades on AA flights within North America, the Caribbean, and Central America, with the exception of upgrades from Business to First on 3-class domestic flights.

As of October 6, 2009, all published fares (including I, O, and Q overseas) are also eligible for award (miles + copay) or systemwide (SWU / eVIP) upgrades!

Wiki: Upgrades | Inventory Classes
FT: AA Now Allows I, O and Q Upgrade Awards (some higher co-pays coming)

FT: Upfaring an itinerary on Hold to an upgradeable fare class (historical interest only)
FT: Upfaring and applying a discount / promotion code (historical interest only)
FT: Mileage Run Discussion Forum: How to specify the booking code on ITA (historical interest only)