However, all costumes have to comply to Washington state decency laws
You mean Oregon state laws? Or Washington county laws? Afterall, last I checked, K-con is held in Oregon. XD
But yes.. the con is generally considered PG-13.. and from what I've seen last year, there wasn't too much as far as borderline naked.. the worst I saw last year was a character with a bikini top and very tight, latex short shorts(a character from Tengen Toppa Gurren Lagenn). Again, that was the worst I saw.. typically, most of the cosplay is well within limits. And they definitely try to make the main halls and non-event areas of the con very family friendly. An example would be.. last year, somebody tried to cosplay as pedobear and they were immediately denied entry due to the nature of the cosplay.
And I did see entire families at the con as well.. adults with children ranging from pre-speech ages, to 12 year olds. May that were with their families were probably 8-10, or younger.
So, me personally, if I had a 6 year old child, I wouldn't mind taking them.. of course, I typically don't attent very many events in general, much less the adult events.
And for the record, this is an opinion from a 23 year old. The most revealing cosplays you'll see will most likely either be pokemon/digimon/whatever gijinka(human forms/cosplay as an animal), and again, a select few from the likes of Gurren Lagenn, or similar animes. But this is nowhere like comic con or dragon con or anything of that sort, that are huge, and often have the likes of models and similarly fit people, dressing in the skimpiest cosplay they can get their hands on.
The way I see it.. as far as inappropriate outfits go.. k-con is basically like going to the beach, on a day when 4/5 of the populace are wearing normal clothes, and the other 1/5 are wearing swimsuits and bikinis. But with a very comic/anime nature mixed in.