I agree with RhineQueen.
Some people can create a picture that looks cool then dissect it piece by piece to explain the reason things were designed in a particular way. Others can think of a picture they want to paint, then create an image step by step until it resembles the idea they were trying to convey. But I think both are highly intuitive and can be equally effective in the creative process, depending on what makes sense to the artist. But due to literary devices such as flashbacks and foreshadowing not all stories have to be told in a linear fashion. Particularly if this one is going to involve time travel at some point.
In all honestly, it probably takes a unique balance of both these aspects to craft something truly engaging for both author and audience. Which is why I'm glad this story is being looked at from three different perspectives opposed to just one. I'd like to think the end result will be far grander than anything any one of us could come up with single-handedly. I just hope we can continue to inspire each other to create... as I think that's the main purpose of this activity even if the story arc still up for debate. Besides, little nuances can be hard to plan if they're just subject to change anyway. But I do agree that structure is key to any successful RP.
Generally speaking I like to think it metaphorically in terms of a dungeon. The players involved start in a room where they find a key which will unlock a door. The new room is comparable to a new idea being introduced to the party, with the key being the hook that invests their interest and the unlock door being the pay-off for their efforts. So I suppose the real question isn't so much thinking about what we should be putting into it, as it is establishing what it is we're hoping to get out of it.