Marysville to Bothell:

SR528 east out of Marysville to SR 9. SR 9 south through Snohomish to Woodinville. Continue south into woodinville on Woodinville Snohomish Road to Woodinville-Duvall Road/175th street. Follow this road across the train tracks and turn right onto Woodinville Drive (you can hop on the Sam River trail in this area too if you are so inclined).

Turn right at next light (it's a mile or two down the road), go across the bridge and up the slight hill. You are in downtown bothell.

SR-9 is a rural road, but has a pretty wide shoulder. If you get tired of the rural, hang a left at any of the following: Cathcart way, SR524/Maltby Road or 228th (big hill) and go left on SR527. That'll take you into downtown Bothell also.