Ah, Xanth. Yeah, I used to read his stuff. The Xanth series started out okay, but it got very kiddie after book 10 or so.
Well, if you like Piers Anthony and both fantasy and Sci-Fi I would recommend that you read the "The Apprentice Adept Series" by Piers Anthony. I actually just reread this series a few years ago and it's pretty good. Not amazing but a lot of fun, and it has lots of gaming in it! There are just 3 books total (there is a second series, but I'm not sure how good that is as I never read it). The books are Split Infinity, Blue Adept, and Juxtaposition. Give those a try...