One thing similar I did was

LAX to DTW
(Gap of 1 day)
DTW to ONT
(Gap of 2 weeks)
ONT to DTW
(Gap of 1 day)
DTW to LAX

On a combo of NW and CO flights

The $3500 cost of two round trips became $400, clearly I had to get a ride to and from the airports.

If you find a local airport to SEA it might work

Steve