I actually like a homemade mix of aspen and double milled cypress mulch for heavier snakes like bigger boas in display type environments. You get the best of both worlds that way. The loft and softness of the aspen combined with the higher humidity abilities of the cypress. I wouldn't recommend regular milled cypress however, it tends to be chock full of huge sharp silvers and often is packed soaking wet. Double milled cypress can be harder to find and a bit more pricey but isn't too expensive when mixed 50/50 with a nice aspen. The cypress also helps the bedding to not compress as much under the heavier weight of a bigger snake as it would with pure aspen.

As some of our female ball pythons are reaching some heavier weights I'll likely to go this homemade mix of bedding for them too.