Look at Ursula Vernon/T Kingfisher (at least the kid/YA focused ones). Danny Dragonbreath might be the right age range for the youngest (text + cartoon), and Minor Mage, Illuminations and Wizards Guide to Defensive Baking would be slightly older (chapter book level).

I'd hold off on the fairy tale (dark. weird) and romance ones (paladins) for a few years yet...

Mine have gone through Paolini (Eragon), Sanderson (all of them. damn he writes a lot), Wings of Fire (Tui Sutherland -- Cute, chapters, skews younger)., Scott Westerfield (Leviathian).