If the booking class is "I", you won't get into United Polaris lounges since those require paid business class tickets.
But since there isn't such a lounge at Washington, you'll be fine.
You'll be able to get into the United Club and other Star Alliance Lounges no problem.
EDIT: I cannot find this information anymore so I'm probably wrong and confused it with the Air Canada Signature Room.
Last edited by Chiller3333; Aug 4, 2019 at 11:01 am