Why not pay a visit to the children's section of your local library and have a browse at what they've got in stock? You may even get an idea from the librarian as to what's in short supply. You're probably aware that there are commercially available story sacks for a number of popular titles, so you'd do well not to replicate them.
Have you thought about one of Kipling's 'Just So Stories' or, perhaps, an Indian story. Diwali's coming up, so you could do the story of Rama and Sita. Some soft toys, a diva lamp etc.