I don't know much about attractions and sites to see, because when I head up there, I only go to ride. That said, there are some amazing roads within your boundaries and some of the usual ones include Southwood Rd 13, Mortimers Point / Foreman Rd, Peninsula Rd/632, Aspdin Rd#3, Hwy #141, Brackenrig Rd, Windermere Rd.
Hwy 518 is a nice technical road - the best parts are between Orville and Sprucedale.
Tally-Ho / Swords Rd: is a short ride to/from the 518 at Orville.
Ravenscliffe Rd is a great road off the 518 at Sprucedale and runs all the way to/from Huntsville. There is a really scenic pull off/ boat launch at Buck Lake.
McDougall/Hurdville Rd combo is a nice and hilly twisty stretch just northeast of the 518
#520 is a nicely paved road from Hwy 11 to Magnetewan.
Old Nippissing Rd is an amazing twisty, hilly run that changes between paved, chip-seal, hard packed gravel and hard packed sand. It runs north/south from around Commanda, through Magnetewan, and meets up with the 518 near Seguin Falls. It was an old pioneer horse/carriage rd and is considered a heritage rd or something like that. It's very technical and of my favourites.
Chetwynd rd is a great run that links up with the 518 on the east side of Hwy11
If you don't mind a little hard packed dirt, then Deadhorse Trail is a fun ride to the western edge of Algonquin and then back to South River. It can get a bit slippery when wet, but when it's dry, it's amazing!
I have not been on this myself, but I have heard fun things about the Bunny Trail north of McDougall.
Just outside of your area is:
Hwy 35 between Dorset and Minden (lighthouse tower in Dorset?).
Kushog Lake Rd - very awesome.
Harburn Rd #19 - more awesome.
Kenisis Lake Rd and Watts Trail - more very awesome.
I camped at Grundy Lake Provincial Park last year and it was really nice. The bridge over French River was awesome and the tourist info shop had nice t-shrts. I really liked the French River area.
5 days - sounds like fun!
Safe riding!