August is prolly the best bet weather wise. Nice and warm and less change of getting rain. If your just looking for a good tour and little traffic stick to the higher series highways as you make your way around. Less people on them but usually more bikes. I can't say too much to the upper end of the provience as I only go there about once maybe twice a year, but for the mid part and lower part you'll find most of the good sight seeing items off the beaten path. You'll get to see lots of tourist attractions on the main roads, but IMO they aren't have as good

A personal fav of mine is heading between New Glasgow and Antigonish (mid way provience) on the main highway you come to an exit (27a I think?) that says Shore Road / Merigomish. Take this one and it will still bring you out in Antigonish near the highway, but you'll get an awesome ride down the shore. Take a stop in Big Island beach, and down at the Amhesrt look off. Both are great for pics, and not many people to bother you
Ride safe, and maybe I will see you guys on the road.