Believe it or not, the city of Seatac is safe. I've lived here for 18 years and and walk my dogs at night every day. Watch the local news and you'll see most serious crimes are happening, in what some consider, the safe areas of the Seattle & county.
We like the close proximity to the airport and shopping and freeway acess. Large lots are still available, but dissapearing fast. Some like that Light Rail is coming in a few years.
Well, that's my 2 cents.

Is it getting better the past five years? Like most places, it's overpriced and is seeing in influx of new residents...and out with the old.