If you’re heading down to to Shmoocon in DC February 15th to 17th, allow extra time if you’re taking Metrorail. Metro is performing platform repair at the Metro Center stop. WMATA recommends allowing an extra 30 minutes. This should start late enough to not be a problem Friday, but it will be annoying Saturday and Sunday.
Parking at the Wardman Park Marriott is $13/hour ($28/day). I dont know of alternative parking down there.