If they are on the same PNR then they will get your baggage allowance too. I couldn't find anything in writing on the US site but AA's policy (which is supposed to be aligned with US) is pretty clearly pointed out here:
http://www.aa.com/i18n/disclaimers/mileageBonuses.jsp
Complimentary checked bags
For our elite status members, we will waive the checked bag charges and you will receive the following:
Executive Platinum members:
Three bags free of charge
Platinum members:
Two bags free of charge
Gold members*:
One bag free of charge
Please ensure that all bags are within current size and weight limits. This benefit applies when traveling in the Main Cabin on American Airlines:
Within the United States
For travel to and from certain locations in Europe to the United States
U.S. territories of Puerto Rico and the U.S. Virgin Islands
Baggage charges will also be waived for customers flying with you on the same reservation, excluding group reservations. To learn more, please visit our baggage page.
In any event I can also state from experience that the policy applies to US as well - flew a few weeks ago on US as an EXP and everyone in my party got my baggage allowance.