Considering how many books there are to read I seldom re-read a book. It happens but only quite infrequently. Only read The Hobbit thrice and LOTR twice for example. Some book series I probably have extra amount of fondness for just because of their length, one of my favorites series for example, being the main series Margit Sandemo has written, is 82 books long, I've just gotten to read 75 of them though because the last 7 have never been translated to a language I can read.

Then there are also books such as the Legend of Drizzt Do'Urden that also clocks in the double digits although not quite as much. And of course I was born into the generation that was in middle school when Harry Potter and the Inheritance Cycle series came out so while they may not be very deep I have fond memories of reading them on breaks during school and during work free summer vacations.
And those are just a small number of the books I've read. I really can't choose any one or even few great books as most all of them stick out in their own way having their faults and merits alike. Many a problem I might have with the writing of R.A. Salvatore I may not have with Tolkien but then Tolkien wrote with many faults that R.A. Salvatore did not.
Currently I have 10 and a half novel waiting for me read them and one manga omnibus so I might be hard pressed to suddenly re-read a book I've read before, it's sort of silly to make flat out recommendations anyway as people in general will have largely varied tastes and some such as myself might just read just about any book they can get their hands on. But to mention where my tastes lie it would have to be in medieval fantasy books. Few things get me as excited as sitting down to read a large book filled with medieval tales of adventure, warfare, politics and sorcery.