There are two airports available for travel into the Washington D.C. area. Both airports have metro access and are also within driving distance of Alexandria.
The first airport, Ronald Reagan Washington National (DCA) is located in Arlington, Virginia, a few miles north of Alexandria, and is also the closest to Washington D.C. itself. Washington National Airport is a hub for American Airlines. For those traveling from Las Vegas, there is one direct flight a day on American Airlines, and one on Southwest Airlines. To travel to Alexandria via the metro, follow the signs for the metro, and enter the metro station at either the north or south entrance, which are both next to the airport security lines. Take either a blue or a yellow train southbound, and exit at the King Street - Old Town station. The blue line southbound train will say Franconia Springfield, and the yellow line southbound train will say Huntington. This ride typically takes 10 minutes.
The second airport, Washington Dulles International Airport, is located in Dulles, Virginia, thirty miles west of Alexandria. Dulles Airport is a hub for United Airlines. For those traveling from Las Vegas, there are typically three direct flights a day on United Airlines. To travel to Alexandria via the metro, head to baggage claim and follow the signs for the underground walkway to the metro station. Take a silver line train towards Downtown Largo, and exit at the Rosslyn station. At Rosslyn, switch levels and take a blue line train southbound towards Franconia-Springfield, and exit at the King Street - Old Town station. This ride typically takes 50 minutes.
A hotel with discounted rates is available for weekend of the wedding. The Hilton Alexandria Old Town, at 1767 King Street, Alexandria, VA 22314, is located directly across from the King Street - Old Town metro stop, allowing for easy access from both airports, as well as to the reception dinner after the wedding.
The wedding is located at the Basilica of Saint Mary, 310 S Royal Street. The best way to travel from the hotel to the wedding would be via Uber or Lyft. Otherwise, it is about a 25 minute walk through Old Town Alexandria.
The reception will be located at the Catholic University of America, 620 Michigan Ave NE, Washington D.C. 20064. There is a metro stop, Brookland - CUA, located at the University. Coming from Old Town, head to the King Street station and take a yellow line train north towards Mount Vernon Square/7th Street/Convention Center. Exit at the Gallery Place - Chinatown station, change levels, and get on a red line train towards Glenmont. Exit at the Brookland - CUA stop. Driving from Alexandria to CUA is about 11 miles, which takes anywhere from 30 minutes to one hour depending on traffic.
A map of the Washington D.C. metro system is available at https://www.wmata.com/schedules/maps/upload/system-map-rail.pdf . To ride a metro train, a SmarTrip card can be purchased at the entrance to any metro station, and can be preloaded with any amount of money. If you download the SmarTrip app, you can tap your phone to enter/exit the metro, and set the card to automatically reload with money. A metro ride typically costs two to seven dollars, depending on the length of the ride. You are not charged for the ride until you exit the station, so make sure you have enough money on the card for the exit fare.