Staying friends with the ex

Breaking up is hard to do. But what about deciding whether or not to stay friends with your ex?

After all, this is someone you've intimately shared experiences and feelings with - good and bad. Should something be salvaged?

On the other hand, it also seems entirely reasonable to love, learn, and want nothing to do with that person ever again.

In what situation is this possible? Is it all or nothing? Are you okay with your SO remaining friends with the exes?