Planning Motion uses the Google Maps application to display itineraries on a map based on the addresses or cities entered in the trip stages.
Currently, Google limits the number of stages that can be added to an itinerary to 25 at a time.
If the trip has more than 25 stages:
It is possible to still get a portion of the itinerary. You just have to select less than 25 stops before asking to create the map..
A stage will not appear on the map if the address or city field is left blank.
When planning one part of the itinerary at a time, leaving the address or city field blank for a stage can be a solution to reduce the number of stages below the 25 limit.
Personally, for long trips, I prefer to create several trips in Planning Motion.
I usually create one trip for each month. That's fewer stages per trip and I like it better for making itinerary changes from the calendar and also for having a monthly budget.