Found this...
D.C. Shuttle Service from Gaylord National
It's easy to visit capital area attractions with daily shuttle services and tours from Gaylord National's front doors.
Downtown DC Shuttle Services provide continuous service to:
Ronald Regan Building (14th Street, Between Constitution Ave. and Pennsylvania Ave.)
Union Station (Bus Terminal/Parking Garage)
Departs 7 days a week from Gaylord National's main entrance, every 90 minutes from 9:00 AM - 7:30 PM.
Shuttle locations and times:
Gaylord National Resort (Main Lobby)
Departs: 9:00 AM., 10:30 AM., 12:00 noon, 1:30 PM, 3:00 PM, 4:30 PM., 6:00 PM., 7:30 PM.
Union Station Bus Terminal/Parking Garage
Departs: 9:30 AM, 11:00 AM, 12:30 PM, 2:00 PM, 3:30 PM,
5:00 PM, 6:30 PM, 8:00 PM.
Ronald Reagan Building (14th Street, Between Constitution Ave. and Pennsylvania Ave.)
Departs: 10:00 AM, 11:30 AM, 1:00 PM, 2:30 PM, 4:00 PM,
5:30 PM, 7:00 PM, 8:30 PM.
Cost:
(Adults) One Way, $13/ Round Trip, $20/ Three-Day Pass, $49
(Children) Ages 3-12: One-Way, $7/Round-Trip, $10/ 3-day Pass, $23. Ages 3 and under: no charge
*Shuttle management will make every effort to maintain the schedule but may experience traffic delays beyond our control, especially during peak business hours. Subject to availability. Dates, times and prices subject to change. Additional restrictions may apply.