Google Maps is an obvious choice for boots on the ground usage, immediate directions, and instant reviews. However, it can get pretty cluttered when you pin everything on the Map.
Wanderlog is an excellent free trip planning app which uses Google Map as its base. With Wanderlog, I can drop pins on a particular day and optimize the route to visit each. Each different day's pins are layered in the map, so I can choose which day to view, thereby hiding the clutter of the other pins from the other days in the itinerary.