BlindPilot....good luck with the job search, however it ends up. I myself moved from ATL to SEA 4-1/2 years ago (after 12 years in ATL) and haven't regretted it for a second, even though the job that moved me here didn't quite work out. For what it's worth, here are my opinions on:
TRAFFIC: no difference. Sucks in both places at times.
WEATHER: Seattle wins. Sure it's dark in the winter, but the summers are spectacular, you don't have to spend $300/month on air conditioning from May through October, and we don't have those annoying thunderstorms that disrupt travel all during the summer.
FRIENDLINESS: no difference. As someone said in an earlier thread, it's about the person more than the place. I've made lifelong friends here in SEA and maintain lifelong friendships back in ATL. And I've got superficial friendships here that won't survive much longer than the ones I had once I left ATL.
AFFORDABILITY: Atlanta wins, because of housing overall. But I'll trade my house here with the occasional views of mountains and lakes for ANYTHING in Atlanta, no question.

Since you say you're in a creative field, I find it hard to believe that you'd find more inspiration in the physical surroundings of Atlanta than Seattle. Atlanta's actually quite a pretty city, and the North Georgia mountains are lovely, but it just ain't the Olympics, the Cascades, and the Puget Sound, not to mention the glorious Pacific coastline.

I've also found more opportunities to follow different intellectual curiosities in Seattle than Atlanta. More lectures, book signings, classes, etc. than Atlanta.

On the other hand, Seattle is a long way away from friends and family on the East Coast--as much as they love visiting during the summer--and it can be harder getting to see them for long weekends and such than when you live in the same time zone.

So whether you'd like Seattle in the long run depends on what's important to you and your family. I firmly believe you can make a great life in either city--good luck with your decision!