Poison Creek campground at Cascade Lake State Park in Donnelly has full hookups (the only unit in the park that does), and is right on the lake. For a campground with more trees, the Ponderosa State Park "group" campground in McCall is good. It used to be a group only area, but they have totally redone the campground with hookups. The sign just says it is a group campground, but it isn't. That one is not right on the lake, but close.
Heyburn State Park near Plummer has water and electric hookups, but no sewer. There is a dump station on site, though. Lots of trees, near the lake and right on the Trail of the Couer d' Alenes bike/hike trail.