As for different types of aspen, you can also get what is called Sani-chips. It's Aspen, but it's in small chips and it is not dusty.

I used it for a while, but I found that my snakes would always get chips in the water bowl, making a mess. I also found that it tended to get all over my snake room...if I'd had a wet/dry vacuum it wouldn't have bothered me as much.

I went back to newspaper.