I'm looking at going to Washington DC sometime next month. I have a $200 (U.S.) travel voucher with AA. My closest airport is YVR. I'm wondering, is it better to fly through DFW to IAD, or to start at SEA and travel through STL? If anyone has done any of these routes, I'd be happy to hear any opinions. I usually do all my flying with Air Canada, and would be interested to hear about AA.