yes, all of AA's 777s are ERs.
AA's average stage length for its 777 fleet (200 and 300s) as of this summer is 5337 miles which is just above the US carrier (AA, DL, UA) fleet average for 777s at 5517 miles. AA's average 777 stage length is comparable to UAs who has alot of 777 flights (at least for this summer) from EWR and IAD to western Europe. DL's average stage length is over 6500 miles. These stats exclude domestic flights, including Hawaii.
Here are the ten longest 777 flights by US operators.
DL ATL JNB 8,433 UA EWR HKG 8,060 UA EWR BOM 7,806 UA ORD HKG 7,787 DL ATL DXB 7,598 DL LAX SYD 7,487 UA EWR PVG 7,384 UA EWR DEL 7,323 DL DTW PVG 7,137 UA IAD DXB 7,069