Surely Prince Caspian is too flimsy a narrative for a feature film. What they should do is link it with Voyage of the Dawn Treader. Silver Chair might just be substantial enough for a film devoted to it. Not sure how either Magician's Nephew, The Horse and His Boy or The Last Battle are filmable at all.
AS a purist I have still not seen TLTWATW.
I didn't think that much of the LION WITCH & WARDROBE...I thought it was a little drab and had the feel of being shot on a sound stage. The action scenes were amazing though and probably worth the price of admission. I don't think the cast has quite come across on screen like Hobbit and Company did.