We recently did a trip to Bentonville and let me just say that if you have not been there or considered it, you need to put it in your plans NOW. You know how when you go to a ski town and every business caters to skiers, talks about skiing, and seems to be designed around the sport of skiing? Well Bentonville is like that - but for mountain biking. Best trails I have ridden anywhere in the world.
For your cold weather entertainment, here is some info:
Back 40: http://www.austinbike.com/index.php/united-states/333-back40
Coler: http://www.austinbike.com/index.php/united-states/335-coler
Slaughter Pen: http://www.austinbike.com/index.php/united-states/334-slaughterpens
Blowing Springs: http://www.austinbike.com/index.php/united-states/332-blowingsprings
Hobbs State Park: http://www.austinbike.com/index.php/united-states/336-hobbs
Yeah, we'll be going back.