If you have not tried the Bothell to Woodinville stretch, it's Northeast of Burke-Gilman, connecting to Sammamish River Trail, going all down the East side. There are maps for this also, and I think REI has a link to a map of local trails. Centennial trail is great as it starts in Snohomish (closer than Marysville) and goes North. Lynnwood now has a trail that I've seen parallel to I-5 at the I-5/405 junction, but I do not know exactly where it starts. There is a trail to check out south of Mill Creek, starting around 164th. I do not know if this one is paved. Some of the trails around Mill Creek are level if you know someone who lives there; these are considered private for residents and guests. Please do be safe and ask a friend to go along Mill Creek and Centennial trails, as some have remote areas and weak cellphone signals.