I don't doubt navigation is important, but I have a hard time believing that a surfer would value bells and whistles to navigation far above and beyond however much they care about the content itself.

I'm talking more about the surfer experience than conversion in and of itself. So beyond the tour and not including the tour, I'm talking more about how a surfer feels about the value they've received once joining a site and whether it was orth their while. What do we feel is the most important thing to them at that point?