http://blogs.technet.com/p-12c_pilot/articles/572336.aspx

Designing Great Missions

Flight Simulator enjoys a very diverse group of users and what makes a great mission for one user may not be a great mission for another, but there are some key points to remember when designing.


and it goes on to describe the types of FS fans (relatively accurately, I might add), and how a Mission -builder (or in generaly terms, a content provider) should approach.

Note that this article may (and probably will) end up in Microsoft's fsinsider page, and may be modified then, so don't repost it, but  rather, just read it from the link.