If you are a group looking for a place to camp or canoe as a group then Algonquin is a great place to do that. There is a campground specifically designated for groups called Whitefish Lake. The sites are set up in a way that a group can occupy any number of the spots and still be beside each other. Whitefish Lake is a great place to do canoe trips as well. Whitefish connects to Rock Lake where there are a number of portages and lakes that you can access.
If you as a group would like to go on a interior canoe trip then there are a number of spots that you can go. If your group is not very experienced then maybe Canoe Lake to Burnt Island would be a good trek. If you have an experienced group then maybe doing a trip up Opeongo would be an idea. The world is yours to choose from!
Enjoy your trip.