Gosh.
I reread
lots. So I won't even bother listing books or series I've reread two or three times.
I think I own every novel and short story anthology Timothy Zahn's ever written (although I've lost one of the
Cobra sequels

) - I was a huge fan before he ever touched on Star Wars! I expect I'm missing a few short stories from multi-author anthologies. But Zahn's fairly high on my reread list - especially
The Blackcollar and its sequel.
Likewise, I have a near-complete Steven Brust collection. All the Taltos books, the Khaavren romances, and
Freedom and Necessity are high on my reread list. I've lost my copy of
Agyar, and I find
To Reign in Hell... less appealing for rereads. I enjoyed reading it once, but I'm in no hurry to do it again.
Lois McMaster Bujold's
Vorkosigan saga.
The Blackcollar may be my all-time favourite book, but
A Civil Campaign, chapter 9, is my all-time favourite chapter. It is ferpect in every way. I used to reread Bujold because they're damned good books. Now I reread them all as an excuse to reread
A Civil Campaign.
David Weber's
Honor Harrington. Honor competes with Miles for everything else, so it's only fair
And Weber's Bahzell books, too, come to think of it - book three's out this year!
I tend to reread
The Belgariad every year or eighteen months, and
The Malloreon,
The Elenium, and
The Tamuli maybe half that often. (If anyone's interested, it takes about a month averaging two or three hours a day to read
The Belgariad aloud...)
Anything SF-related associated with David Drake. I found his fantasy trilogy... okay. But
Hammer's Slammers,
Northworld,
The General,
Belisarius, and numerous one-off novels are all fantastic.
Most of Lackey, although the Gryphon series didn't grab me. But all the rest, I'm very fond of.
And though it's been years, I think my
Watership Down count was up to about seventeen...
-Hyp.