Comment William Sleator (Score 2) 726
As a kid/teen, some of my favorites were by William Sleator. A lot of sci-fi staples were introduced to me in his books (cloning, 4th/5th/nth dimensions, black holes, telepathy, time travel). My favorites were House of Stairs and Interstellar Pig.
I also enjoyed the Tripods series by John Christopher.
Also, I'm seconding the Danny Dunn and Tom Swift series. I think the series of Swift I read was the Tom Swift, Jr. from the 50's and 60's.