Upgrades

How can AA elite members get upgraded on a domestic codeshare?
How do American systemwide upgrades work?What are systemwide upgrades on American Airlines?Does American Airlines give free upgrades?Can I upgrade som...
Are there any ways to get American Airlines systemwide upgrades, apart from having Executive Platinum status?
Will American Airlines extend systemwide upgrades?How can I get a free upgrade on American Airlines?Can you buy upgrades on American Airlines?Can you ...