After taking the time to better look at what sort of places were coming back from Google with the "Where to stay near Seatac" question, I realized that most of the results aren't great places to stay. So, I have done a little bit more research and heres' what I've come up with for Bed & Breakfasts (relatively) near Seatac. Let me start off by saying that there's not much immediately surrounding the airport. That has a wide range of hotels: from nice Business suites (Hilton, Radisson, Double Tree, etc.) to budget motels (Motel 6, Super 8, Days Inn), to scary places (Jet Motel, Seatac Inn; maybe they look fine on the inside, but the outside makes me want to run away). So, I'm going to try to list things that are within about 10-20 minutes of Seatac. I'll also try to group them by neighborhood, closest to more distant.
Normandy Park is a wealthier community that has a lot of views of Puget Sound and Vashon Island.
Kent is east across the valley from Seatac. It's a short drive from the airport and still quite easy to get to downtown Seattle. I probably would not be recommending anything in the Kent area, except this one location seems to stand out as being a really interesting house on a historic lot (it still has a good sized lot that has not been completely subdivided).
West Seattle is a bedroom community for downtown Seattle. It has really grown in the last several years, taking on a much heavier metropolitan feel.
I've left out anything in the downtown area. There are a lot of options around there. Here is a starting point.