just got back from the metro parks cleveland zoo this weekend and thought about a new way to do the maps.  they should give you a durable plastic one with a gps tracker in it.  Then you can have a dynamic "you are here" light.  for large groups or families that split up, you could add their tracker to your screen, so that you know where they are all the time.  that would help coordinate meeting times, meals, and just supervision. 

 I was just thinking a static layout of the map painted on the screen, but maybe it could be more like a tablet pc, and the park can update if the animals are outside that day, if a new exhibit is open, the times of shows, etc.  Certainly wouldn't be cost effective to replace maps, but maybe for $20 extra a group could use these, then i bet they would catch on.