Your Friday afternoon journey from dca to iad should be easy any way you take it but if your morning flight is delayed even just an hour I'd suggest against taking a car/Uber. Reason is the road from dca to the beltway is hov-3 afternoons otherwise consider it an as afternoon toll road and it's not always cheap. $9.25 was the toll for a 3:15pm entry into 66 continuing tonthr dulles toll road (which is not a toll road if you are going to dulles airport) Friday the 24th. Expect it to be much higher as the weather gets better.