I have read the first two books in the Song of the Lioness quartet over 20 times (I lost count at 20). I discovered them when I was eleven years old and I just fell in love. I checked them out countless times from the library and racked up huge fines before finally buying hardcover editions in high school (yes, I still have them, and yes, they have the original 1980s cover art, though I didn't purchase them until the 90s.) I've read them sporadically throughout the years and my enjoyment hasn't lessened with age. Nostalgia, it's a powerful thing.
(Note: I strongly disliked the last two books in the quartet and have read them maybe five times, hoping each time that I'll like them better but I always end up disappointed.)