I recommend the Young Wizards series by Diane Duane, starting with So You Want to Be a Wizard. Wizardry here is partly a matter of aptitude, partly of study, but mostly of need and commitment; you find the chance to become one if the universe needs you to devote your life to slowing down entropy. And oh, it is fun. I'm not actually doing very well with description right now, but I'm sure somebody else could add on.
Sabriel and Lirael and Abhorsen by Garth Nix. Sabriel is part of a tradition of sort of anti-necromancers that must regularly lay the Dead back to rest when they've been dragged back upriver and are shambling around. But she wasn't expecting to take over her dad's job quite so early.
Pamela Service has written a whole lot of novels, generally easy reading; she does reuse patterns somewhat, to the point that I started noticing a bit of a formula feeling eventually when I tore through several in a row, but it's a pretty good formula as they go and she does have a lot of variations on it. I may have just overdosed. :P The ones I love best are Weirdos of the Universe, Unite!, in which a couple of kids end up fending off an alien invasion with the help of (among others) Baba Yaga, Siegfried, the Wild Huntsman, and a tribble; and the pair Winter of Magic's Return and Tomorrow's Magic, which is... um... post-nuclear-apocalyptic Arthurian fantasy.
And while we're on Arthurian stuff, everything by Gerald Morris. I think he started with some of the better-known pieces and later proceeded into more obscure bits, and he turns all of them into really fun novelizations which combine fondness for the characters with real foibles and mix seriousness and absolute hilarity wonderfully. I love them.