Thanks everyone for their responses. I guess this gives me enough reasoning to ask my finance folks about it.

BLI-Flyer, I've not had to produce a receipt for the actual work-related flight when I've included a personal trip. For example, when flying from DCA to LAX for work, and then from LAX-DEN-DCA for a stop to visit friends, I would print a copy of the actual ticket receipt (including the personal stopover) and then something from the airlines that showed the market-value of the work-related trip, my company only paying the work-related portion of the trip.

Perhaps this same approach would work... print something from the airlines that shows the market-value. How have the rest of you dealt with this?