Dryer is dead on. I would add snow to that list. You bring what you need to fit the circumstance. Both map/compass and GPS take some proficiency to use. Over the past few years going out with people who are still getting used to their GPS, I can tell you there IS a learning curve on it. I still only use map/compass, but my background experience with this culiminated with being paid to accurately mapping geologic contacts with a Brunton compass (also known as a pocket transit) using eye height and pace as well. Obviously this is pre GPS. I am comfortable with that and have a slight distrust of things with batteries. However, travel in flat terrain and snow is very challenging using map and compass. But snow is the one in particular which makes me want to buy a GPS unit.