I think Tom would be a much more promising candidate (I'll have to check how Burner did in his part of the district, but probably not stellar), but the 48th basically includes staunchly Democratic rich areas plus the staunchly rich, Republican-leaning Gold Coast. The GOP made no friends in the district even during 2004; Bush's performance in Bellevue and the Gold Coast was down in every single precinct (and KingCo has precincts of only a few hundred), which was impressive. It's the most affluent legislative district in the state (I'm 95% sure). Kerry won it by 14 points, compared to his 8th-wide margin of 3. He probably can't improve hugely there, but he's the kind of candidate who could do well elsewhere.
Tom, assuming he can appeal to the exurbs (where Burner faltered), would be one heck of GE candidate. But the grassroots
Burner. Who actually isn't that awful of a candidate, but already spoiled herself by a ultra-repetitive ad campaign in 2004.