After you pass Whedron, the current dies, and you have to muscle 4 miles to the dam. At the dam, you have a rough uphill and downhill portage to get back in the water. There is a parking lot to potentially end the trip, and next time, that is what I'll do.
Ottawa is not for canoes. There are way too many rookie powerboat owners who are oblivious as to how much wake they are creating. We came close to spilling on 3 different occasions. I doubt I'll every canoe through there again. Kayak might have been a bit better, but it was really wakey.
Yorkville to Millington is a simple float, very remote.
Millington to Sheridan is just as remote.
Sheridan to Whedron involves the awesome dell areas
Whedron to Dayton dam is a hard paddle on a wide river, with not as much scenery
Dayton to Ottawa has some scenery, but is a trap for small boats.