WA - Spokane to Everett US2 or I90?

The slow Sunday afternoon traffic on US2 is mainly in the set of small towns once the highway emerges from the mountains (Gold Bar, Sultan, Startup, Monroe - order may be wrong). I don't there is a stop light until Monroe, but the mix of local traffic and highway traffic can create slow downs, and more than normal number of accidents. Monroe has several stop lights, and lots of mall traffic. Once past that US2 is divided and flows well (usually) to the junction with I5. On a Sunday afternoon, traffic north bound on I5 from there should be smooth, though it doesn't thin out under the Arlington exit.