House of Many Ways by Diana Wynne Jones, a sequel to Howl's Moving Castle, is the story of red-haired, bespectacled Charmain, a girl who loves books but doesn't care for hard work. Her dream is to work in the Royal Library. Instead, she's tasked with housesitting for her great-uncle William, a wizard. The house is full to the brim with magic. Strangely, it seems to contain pathways to many different places, including the Royal Palace.
All her life, Charmain has been taught that magic isn't quite respectable, but she can't resist trying a few spells from Uncle William's magic books. To her surprise, she seems to have a knack for it. Peter, a directionally confused boy who hopes to be the wizard's apprentice, shows up, and things spiral out-of-control. Sophie and Howl (disguised as a little boy), put in an appearance, along with Calcifer the fire demon.
13 Gifts by Wendy Mass is the tale of a special summer in the life of a girl who is about to turn thirteen. Tara, the appealing but antisocial MC, reminds me a bit of Ant in Choldenko's Notes from a Liar and her Dog. After getting in trouble for participating in a social--but, unfortunately, illegal--activity with some kids from her school, Tara is sent to spend the summer with relatives she scarcely knows, in a strange little town called Willow Falls. Quirky but likeable characters fill the pages of 13 Gifts. It's a satisfying story, and a great example of magical realism for the middle grade reader.