There are two AA advantages:

On A DOMESTIC 25K award: You can stop-over anywhere (does not have to be a logical connection city) and open jaw if you want.

For example, I have used: SNA-ORD-YYZ destination, YYZ-DFW-DEN stopover, DEN-DFW-SNA.
Or an example with both stopover and open-jaw:
ORD-SNA stopover SNA-SFO-YVR destination YVR-DFW-ORD-CID return open jaw

On an INTERNATIONAL itinerary, AA also allows both a stopover and open-jaw, whereas certain other ailrines offer one or the other and restrict the routing more than AA does.