So you would be helping a travel agency sell more trips because of who you and your wife are. Would you be leading a tour which you must create? Take care of reservations, tour buses, etc? With how many people? On your own time?

I think you should figure out what your time is worth (both of you) each day in order to come up with your fee. Have them fly you in business class and provide you with a suite at the hotels they select. You will be working and thus you must be paid accordingly.