I road from the south side of lake sammamish to Kirkland for nearly a year until my office recently moved. I road along W Lk Sammamish Pkwy then took Northup the rest of the way. This goes right past the junction of 405 and 520. Once on Northup there isn't any bike lane and later no shoulder. Riding at night and in the rain down there would be rolling the dice. In general, I found Bellevue drivers to be intolerant and sometimes hostile. In daylight, I could do the ride every day. After daylight savings ended I was thankful the office moved to a location more easily accessible by bike in traffic and the dark.
Coming in from the the north would be much easier than traversing Bellevue.