Flying to Seattle via Chicago a couple of years ago my flight arrived at Chicago early.

At AA transfers they very helpfully gave me a boarding pass for the correct connecting flight I was booked on but placed me on standby for an earlier flight due to depart within 30 minutes. As a Gold (OneWorld Emerald) my standby ticket was given priority (number 1 in a queue of 15+ people) which resulted in me being able to take the earlier flight while others weren't so lucky... so there are some perks!