Thanks for the tips. I had a very easy time getting out of Dulles. I was first off the plane (helps flying at the front) and thanks to some advice off here I managed to be first off the plate mover. Nobody ahead of me at either immigration or customs and despite the immigration computers crashing from the storm I was in cab less than 30 minutes after landing. Pretty impressive but I gather it's not always like this.

The roads were clear and I was at my hotel in about 30-something minutes. Total including 20% tip was $70.

Thanks again for the help.