This permnant populaire (RUSA Approval Pending) starts/ends in Columbia Point Park. There is plenty of public parking, restrooms and a water fountain at the Park. Also near some nice restaurants (three within eye-shot of the park), and my favorite coffee shop in the Tri Cities.
The first half of the route encounters no services, so leave well stocked when you head out. The route/map is on ride-w-gps. And the cue sheet is here. The route may be completed in either direction. I prefer clockwise - no idea why.