Admittedly, once you cross off the county races whose partisan primaries are mostly foregone conclusions (except for council districts #1 and #9, where there are real bloodbaths due to incumbent council members getting redistricted together, but where I don't happen to live), and all of the races that only have two candidates (and hence no primary), the only thing of importance being decided tomorrow is (drumroll...)
the question of which of the 12 Port Commission candidates (yes, there are really that many) advance to the general.
Still, for a government entity that manages to stay mostly invisible, the Port of Seattle Commission sucks down rather a lot of tax money -- in fact, it seems Seattle is one of the only ports on the west coast that's not hugely profitable and thus needs a tax subsidy in the first place, so something's already wrong with this picture.
The really hard race is going to be Seat #4, where Pat Davis, a nominal Democrat who 20 years ago ran as a reform candidate, stayed too long, is now apparently in bed with the Wrong People, and been on the wrong side of altogether too many 3-2 votes (e.g., against domestic partner benefits, in favor of certain real-estate giveaways...), but she's the incumbent and has a shitload of money. The other candidates in this race are two unqualified nutcase Republicans (Pope and Walker) and Jack Jolley (former Microsoft Assistant Treasurer who seems to be generally clueful and Lawful Good), meaning if Jolley doesn't survive the primary, then we're stuck with Davis or worse for another 4 years.
The other tossup is (open) seat #3 with former King County Auditor Lloyd Hara vs. a sea of randoms.