Before you plan to cross you may also want to check the food restrictions.
I think some meats, fruits, veggies etc can not be imported.
Also, NO GUNS. Not trying to start anything, just pointing out that this is an issue where border guards are VERY strict and you don't want to even think of the hassle.
As for destinations check out http://www.ontarioparks.com/
for a list of some great Provincial Parks.
As for city destinations, Ottawa, Kingston, Toronto (Bronte Creek PP close by).
If you are interested in going North you could look at Algonquin PP or any number of other parks in the (Near North) from the website.