I have been to northern Manitoba, Lynn Lake to be exact. The paved road runs out in Thompson but they grade the gravel part once a year, whether it needs it or not. Stay at the hotel, they have a great bar and a Ms Packman game. Don't set your beer down or the Indians will grab it. Steak sandwich to die for. Ice is gone off lake in late May, great fishing (norther pike).
La Ronge Saskatchewan. That's about as far North you would want to go in Saskatchewan. Last stop light is in Prince Albert (PA as it is know locally), but the pavement runs all the way up to La Ronge. Be careful where you park, Indians will grab it. Probably one of the best places I have ever been to see the northern lights. Lot's of Americans running around looking for pot before they head up to fishing camps during warmer months (June-July). Wear plaid flannel shirt and ask for chips and gravey, you'll fit right in.
Gord