I remember reading a lot of hardy boys books in grade school. That stuff had to be terrible, but I thought the hardy boys/Tom Swift crossover series was the shit. At some point I got a hold of some better stuff. White Fang was one of the first really good books I read. I got into science fiction with an Isaac Asimov short stories anthology and from then on science fiction made up the majority of my reading. My dad introduced me to Kings Dark Tower series when I was around 11 or 12 as well. I may have even read a few RL Stine books, but they must not have made much of an impression.
I still have many of the books I read as a child. From the colorful dinosaur books that convinced me I wanted to be a paleontologist, to the Asimov book that has the fascinating story that describes mans evolution into god (imagine reading that at 12), to the first edition of "The Gunslinger", before king went back and dumbed it down. That last one has been read so many times its falling apart. I almost forgot about Anne Rice. I think I read all of her vampire chronicle books at a very young age as well.