Birthday Party Trek
You can go from “Marymoor”:http://www.metrokc.gov/parks/rentals/pomjun99.htm right by the tennis courts and pick up the trail there. From there, King County has done a great job of putting in underpasses for bicycles through all the major streets. It is about 7 miles and very flat up to the “Red Hook Brewery”:http://www.redhook.com/happs_forecasters1.htm where they have the Forecasters Pub. It is open for kids during the day and it has good sandwiches, burgers, and of course beer too. Then it is another 4 miles or so up to the Bothell point where you can turn around, or make your way up into the Burke Gilman.
Go early on Saturday and Sunday with the kids and you avoid the bicyclists streaming through. Bring some food for the ducks too if you like.