I'm not sure I'd want to see this. Spider-Man and Batman are too different, and I like them both for different reasons. Most of the time, crossovers don't do much for me. The reason Roger Rabbit works is because the classic characters like Bugs, Dumbo, etc, just have cameos. It has an original cast of both humans and animated characters that provide the primary entertainment. Not sure how that would work in a superhero context, other than inventing a new superhero and supporting characters.