I guess.. I have read the Nausicäa manga, which is my favorite work by Miyazaki. I would recommend it if you haven't read it, the movie only covers about 1/4 of the manga.
I also started reading Wizard of Earthsea, which I haven't finished, but I have so far loved. Ursula is one of my favorite writers, but this is my first time delving into her fantasy work.
Howl's Moving Castle is on my to read list, hopefully I get to it one day!
It's funny, I just finished watching Nausicaa for the first time and it really felt like there was missing narrative. I loved it but I could tell there was more story missing. I'll check it out!
Also good tip about Earthsea. I have heard of a book before and it sounded good
I read manga of Nausicaä and I really recommend it because movie covered only a beginning of the series and changed a lot to make it work and because it is a great manga in general, my favourite anime/manga work.
I love that series! Castle in the Air didn't really grab me the same way but I was glad to read all three. I didn't even realize Howl's Moving Castle was a book first, and I'm so glad I saw it recommended and immediately checked it out
Edit: Just found out The Secret World of Arrietty is based off a book called The Borrowers so I put in a hold for that at the library, thanks for the idea!
Will probably read Kiki's Delivery Service, too, but I think we only have the first of the series in the US
The best way I can describe the Howl books are a cozy, blanket by the fireplace feeling. To me it's similar to the movie where the plot is fine but it's more about the atmosphere and tone.
On the Borrowers... I remember the 90s movie, didn't know it was also a book!