I would love to see a trilogy of big, long films (as in The Lord of the Rings), based on one of Iain's 'Culture' novels but agree that the scale of his stories is probably too vast for a standard film. I enjoyed the recent adaption of The Martian but when you see what they had to cut out & how thinly they had to reduce the detail in the book to make their film, well, with Mr. Banks' works they would struggle. Perhaps, rather than do one of his books, a Culture-based film could be made? Retaining the style of characters, the humour, the darkness, the Ships & Droids & Habitats, etc. but a new story designed for film. It's a wonderful Universe he created & the Culture is an interesting civilisation, there's clearly scope for more great adventures based in it.