Chilcotins. Nothing more to be said. If you want a true back country, alpine adventure bike packing type trip, it's the best.
Get the 'Southern Chilcotin Mountain Trail Map' by Trail Ventures BC.
http://www.trailventuresbc.com/map-areas/south-chilcotin/chilcotin-introLee Lau has a very useful site with maps and inspiring adventures.
http://www.leelau.net/index2009.htmStart planning!
Good Luck.
Adam.