I've been using Lizard Liner (a green felt carpet)as a substrate. I like the look, it's easy to spot clean and I can feed w/o worry of impaction. Of course, does nothing to help humidity. I change out once a week with a fresh piece no problem.
I also like the look of Reptibark, etc. I've been afraid to use it because I feared I wouldn't be able to do a good job of spot cleaning. Is it as easy to miss messes as I think with Reptibark (and similiar) substrates. Now my little guy is small and messes are small, but I was thinking when it gets bigger (and leaves bigger messes) I might switch to another substrate - thinking it'd be easier to find the 'presents'



But if it's just laying on top it's not to hard. just pick it up and some of the messed on substrate and replace it with some clean stuff.