I enjoy reading adaptations, particularly when they're fairy tales, because I like to read different interpretations of familiar stories. If you want to read a variation of The Wizard of Oz, you can't go past Wicked by Gregory Maguire (which the musical is based on). Danielle Paige has also written a great series about Dorothy's adventures.
Alice in Wonderland has also had some great rewrites, by Gena Showalter and Christina Henry, and Beauty And The Beast was recently rewritten as Hunted (another well-written and interesting book) by Meagan Spooner.
Another oldie (but a goodie) is Angela Carter's The Bloody Chamber, where she rewrites popular fairy tales with a new slant.
I've really enjoyed reading all of these adaptations. I can't say they're better than the originals, because they are so different, but I think that's what makes them so compelling to read.
Great question! Thankyou for reminding me about The Bloody Chamber. There is a copy on my shelf that has been sitting there for years and I've never read it. Must get around to it.
Oh and I thought of another- Nalo Hopkinson's Skin Folk has some fairy tales with a Carribean flavour, including some of European tales she has changed to fit the setting. I love her style, and it makes a change to read fantasy with some people of colour as main characters.