Synchronize!
One essential step I haven't yet mentioned that you must do if ever you travel with more than one camera: Synchronize all of your cameras' internal clocks! I make slide shows of my favorite photos when I travel. It's a visual diary, endlessly entertaining for me to use to reminisceand proof that the trip actually happened when I arrived home, and suddenly feel strangely like I never left! Despite the three cameras and their various naming systems for files, syncing clocks makes it easy to sort images by capture time. (I'll explain how to use Photo Mechanic for this purpose shortly.)