Bear Creek is sick, so is Vernon and Peachland. Penticton (Naramata) is another good spot. Lytton (Fraser Canyon) has the sickest riding spot in the province. Go to the Monkeywrench Cross-country on the July 1st weekend and you'll see what I mean.
www.okanagantrailriders.com
www.okanaganmotorsports.com <- local GasGas dealer
I race in the Okanagan quite often and it really is that sweet. The Kootenays are very good too.
NOTE: Stay on the trails, don't freeride. We have major land issues up here, so don't just cruise through the woods. It is frowned upon up here.
Let me know if any of you guys are coming to the BC interior (Kootenays or Okanagan) and I'll try and meet up with you.