AA is $150 for the first ticket, $25 per additional on the PNR. At least, that's what the change fee is, assuming redeposit is the same. However, AA will let you change anything except the origin or destination airports, or going between OW and non-OW partners, without incurring a change fee. If you move the trip up to within 21 days of the day of the change, they'll charge the $75 close-in fee, though. If you think you'll take your trip, just push the dates out.
One more good thing about AA awards - they treat at least JFK and LGA (not sure about EWR) as co-terminals. That means that if you're changing dates just to push without incurring a fee and XXX-JFK-YYY isn't available on AA, you can book XXX-LGA (break) JFK-YYY with the first segment on US, for instance. I actually did just that on our BOS-YVR trip. I have zero intention of flying BOS-LGA and cabbing to JFK, but the JFK-YVR segment on CX was there on a better date so I took it to preserve the origin and will wait for BOS-JFK to open. If BOS-JFK never opens, I'll drop the segment and fly PWM-JFK on B6. AA also doesn't charge change fees to drop segments, even if it changes the origin.
I hope that helps with what AA doesn't charge for. AA is incredibly flexible.