As one who would like to take a trip in the Sierras next year (a totally unfamiliar area as well as terrain I've never experienced), the prospect of getting specific trip info is exciting.
I think that a structured format would be essential to successful presentation and searchability. If the key data were available on a single initial trip report page, other more extensive detail, including pictures, could be linked for those desiring that level of information. This would streamline our exploration process, make printing of these "one page" summaries efficient for future review.
The inclusion of lat/lon or UTM cordinates for key points (trailheads, trail intersections, and other points of interest) would facilitate trip preparation for those of us who use computer mapping software to custom-print our topos. Although we don't need maps ala Backpacker magazine, the key points coupled with a general description of the trail and route would be most helpful.
Specific directions to the trailhead, if obscure, could be one of those "linked" details. Also permit, elevation, weather/seasonal info, local transportation, etc.
Needs to be easy for the reporter but specific and detailed enough to allow route planning by one who hasn't hiked the area before.