Just to get this immediately out of the way, I didn't watch all of them. Here's what I was able to get:
Castle of Cagliostro, Nausicaa of the Valley of the Wind, Castle in the Sky, My Neighbor Totoro, Kiki's Delivery Service, Princess Mononoke, and Spirited Away.
Also, I skipped over Grave of the Fireflies (for now) because while Hayao Miyazaki was involved in it (I think), he wasn't the writer-director like he was for the others. This was for Miyazaki, not Ghibli; hence Cagliostro and Nausicaa.
Castle of Cagliostro, Nausicaa of the Valley of the Wind, Castle in the Sky, My Neighbor Totoro, Kiki's Delivery Service, Princess Mononoke, and Spirited Away.
Also, I skipped over Grave of the Fireflies (for now) because while Hayao Miyazaki was involved in it (I think), he wasn't the writer-director like he was for the others. This was for Miyazaki, not Ghibli; hence Cagliostro and Nausicaa.