Redmond, headquarters of Microsoft, has several nice running options. From Redmond Town Center, home to lots of hotels and restaurants, the Sammamish River trail runs 2.8 miles to NE 116th St. You can do a 5.6 mile loop along either sides of the river.
About 5 miles east is the pleasant Redmond Watershed that runners can utilize while visiting. This is actually the eastern terminus of the Burke-Gilman trail. Your run can be anywhere from a couple of miles to 14 miles.
South of Redmond Ctr. is Marymoor Park, which has miles of trails, some interior and others along the the river. About 2 miles from northern to southern end.
Marymoor Park Map