It turns out that when I head up to NYC in two weeks, I will be flying instead of taking the train. Round trip on Acela is usually around $300. On Christmas Eve, there are no Acela trains after 3 PM and the prices were still pretty expensive. So I checked United from IAD to LGA and got myself a ticket for $120 round trip! I get into La Guardia at about 4:30 Friday afternoon. And my flight back to Dulles leaves La Guardia at 7:30 Sunday evening. And it was $200 less than what I would have paid to take the train. I’m glad I checked!