2. Harry Potter
The Book: J.K. Rowling took from just about every possible source to write the smash series that made an entire generation fall in love with reading. The series was huge, encapsulating adults as much as the intended young audience (leading to creation of perplexing adult covers). For all the criticisms of simplistic writing and flimsy plot, theyre an impressive representation of growing up, with characters developing with time as much as the mentally scarring events around them.
Why It Shouldn't Have Been Adapted: As you know, it already has, to much fanfare. The Harry Potter films aren't inherently bad, but their success is essentially piggy backing on the success of the books. If theyd been released once all the furor had died down, people would have been a lot less lenient on their many problems. Ignoring the books period settings and liberally slicing the plot for no narrative reason, theyre really just average blockbusters. The real issue is that the world Rowling has created is so dense and tightly woven that its impossible to faithfully adapt it to the big screen; you just can't plan seven films at once. But if youre doing a HBO-style miniseries, taking one book a series, I'm listening.