Ditto on "The Crying of Lot 49," but I found "Mason & Dixon" quite rewarding. Nonetheless, for a general reader it suffers from length and density.

The thing about Faulkner is, do you start with something with a nice, neat, single narrator, told in more or less standard English (which can be fantastic literature) or one of the more narratively adventurous works (which are fantastic in addition to being spectacles)? For a general reader, I lean toward the former, since it introduces you to his themes and settings and attitudes without being distracted by trying to figure out what's being said.