If you liked the Half Magic books (which I just adored as well), did you also read the E. Nesbitt books? Phoenix and the Carpet, Five Children and It, etc?
Some years ago, I decided to buy the books that I'd like, so that I could read them again - and I decided I didn't care if people thought they were too childish to buy. I have Edward Eager's books, the Edith Nesbitt ones, and then I bought some old ones that I remembered (Dogsbody), and discovered Diana Wynne Jones' other wonderful books.
Somehow, I need to find the books the Tree that Sat Down, Stream that Stood Still, Mountain of Magic - I recently managed to find which books they were from my old memories of reading them, but they're now out of print and pretty expensive to buy.
Looking forward to sharing them with my children - recently read my 5 year old a short version of The Little Princess, which she loved, so must see about some others!