Why is there another series on the schedule? Read this article.
The gist is, more manageable routes, but self-supported.

This route takes place on Sunday. That gives you time to get to Seattle, and then leave on the Sunday to get back on the Monday, the 30th (and the 1st of July is a holiday).

It's a known route, so should be decent roads, and a good time. Getting into Seattle late should be fine, there's plenty of places to stay, and u-district is open late, or you can go further or closer (a few options in Woodinville).