Public transit is probably your best bet. This link above has more information.
That said, something to note:
According to the PR material from USFS here is the top 5 attended Skate America events (cumulative):
2008 Everett - 29,477 (big boost from Yuna Kim's presence at the event)
2002 Spokane - 28,644
2010 Portland - 23,362
2004 Pittsburgh - 17,906
2001 Colorado Springs - 17,312
Those kind of numbers must resonate with USFSA. Combined with the fact that Kent got a positive plug from Disson Skating for a great turnout at a show there in January, explains why they ultimately choose another West Coast city.
Also, since figure skating is so popular in Japan, the Seattle area is an ideal place because there are a lot of nonstop flights from Toyko to Seattle and Vancouver (about 3 hours north) and despite the terrible jet lag (as you cross the int'l dateline) -- the flights themselves are relatively short (12-13 hours). Perhaps they took that into account?
I think the USFSA is really underestimating this area because skating is quite popular in this part of the country and I think turn-out would be just awesome for anywhere north of Washington D.C.
It's been over 10 years since any east coasters could even poke Nationals with a 200-mile stick...