Welcome to Colorado! We're full, but always make an exception for out-of-staters on orders. ;-)
Pretty much everything 'near' Buckley is going to be west of Buckley - in the mountains. As long as you're geared to match your tires you'll be okay in the rocks, but getting up I-70 at anything resembling highway speeds might be difficult. www.traildamage.com
for trail options in the area, or post up in this section as well. As spring starts to warm things up there will be more opportunity to hit the trails; right now many of them are still snowed in.
My experience with the base doesn't count. I was at the Navy/Marine Corps Reserve building in '89 until I saw the light and went active.