Review:

Review your trip with the participants to find out what they liked & didn’t like, what you can pass onto the next group doing the same type of thing.
You can do a post survey like the survey’s that helped plan the initial trip.  I would recommend doing this close to the end of the trip so it is fresh in the minds of the group.

How did you do on your budget?

Were you under budget, over budget or on budget?  Look at your per item costs to see how they compared with projections.  This information is very valuable for planning for another big trip.  Also it would give you an idea of how to alter and maybe what might need to be dropped in the future for cost reasons.
When we were planning out the 2011 trip we had a hard time finding numbers for a lot of costs from the 2006 and if our budget was on track.  We knew we came back with money but not a lot of details.  It was my mission to keep track of this information better.

Some items I learned from the last trip:

Unexpected Costs – Tips, change in camping fees, Misc. expenses -Keep better track of non-receipt costs like Laundry & Showers.