good scenario design

[t1M0t8yk]

I am a PG noob, although a very experienced wargamer, including many other tactical systems. I think an interesting topic for discussion is what distinguishes a well-designed scenario from one that is not well-designed. I searched the PG forums and didn't find much discussion about this. I acknowledge this could be because of my own limited capacity for conducting an effective search; if so, I welcome responses that point to other threads about good scenario design.

Hopefully though this is a fairly fresh topic. The PG-HQ database is great, and if accurate indicates what people like. Certainly though a real discussion beats data mining; after all, people often don't indicate in the database *why* they like a certain scenario.

What do you think are features of well-designed PG scenarios? What are examples of scenarios you consider well-designed, and why? Which PG designers do you think are the best? Which PG modules or books do you think have the highest proportion of well-designed scenarios?