Which would you choose if you had a connection at IAD in mid December a flight with 6 hour layover or one with two hour layover?
take the 2 hr. if your west coast is delayed at iad, i would presume the outbound connection will also be delayed. i think 2 hrs is plenty of time to make just about any connection at iad. i also presume the weather is never bad on the west coast, and flights there are never delayed.