A dream sequence.

What makes a dream sequence interesting?

Hmmm. What do you mean by 'interesting'?

I would think that what makes one interesting is definitely the amount of things there are. If you have a deep, serious book like 'a fault in our stars' or something like that, then one or two huge, meaningful images would fit nicely, but if you've got a giant adventure book, lots of little interesting ones might also fit. For example, a mystery book's sequence might be wholly made up of little clues that the detective has to figure out. It all just depends.