I’d been reading Diane Duane’s work for years when I was recently (2004-ish) introduced to her YA series about young wizards, which began with So You Want to Be a Wizard, and continued from there. (I’ll confess that I first read her it was a Star Trek novel – see – told you I was a geek).
This series, though, is completely original. It ties into another work of hers The Book of Night with Moon which is a must-read for cat-lovers everywhere, but can be read without that volume as well. The characters are, for the most part, realistically drawn gifted children, and the plots, while resolved, always have some loose thread that could be a sequel, or just a tangent.
I read them as an adult; so should you.