I think if I were you I would cross at Sault Ste. Marie - less traffic congestion than taking the 401/400 highways in Ontario and Hwy. 17 is a very pretty drive from Sault Ste Marie to Sudbury and south to Grundy on Hwy. 69. Keep in mind gasoline is cheaper in US but your Am. $ will go further in Canada this summer.
I would definitely make a reservation at Grundy. You might also enjoy Killarney P.P.which is about 45 miles west of Hwy. 69 and south of Sudbury.
Reservations would be necessary there as well. Ontario P.P. are brutle to get into during the summer months, especially on weekends.
Have a look on line at Fairbanks and Windy Lake P.P. which may be easier to get into. Both are located north off Hwy. 17 and West of Sudbury. I have not been to either of those parks in years so I don't know if they would meet your wishes or not.
