Topographic maps from the U.S. Geological Survey or another source can assist in planning an itinerary to a wilderness region. Backpackers and cross-country hikers especially need these maps to route their travels along an efficient route (often with as little change in elevation as possible), avoid obstacles (like landslides, deep canyons and other generally rugged terrain), and locate water sources and potential shelter.
You can also choose a detailed-enough topographic map and keep it handy on treks to ensure your personal safety. Sharing your route with friends and family, not to mention other members of your own party is made far easier with the detailed geographic information coded in a topographic map. If you do find yourself off-course by rough weather or otherwise threatened, the map can help you find springs, high points (where cellular phone and GPS reception might be stronger), nearby roads and buildings.
They can also help read the landscape through a topographic map to identify likely locations for game and fish. For example, if you're pursuing elk during a chilly autumn, you might focus on south-facing slopes that can attract thermo-regulating animals, not to mention natural bottlenecks of terrain that concentrate moving herds. Adventurous backcountry anglers can seek out high-elevation lakes that may only be accessible by foot.
Many people find well-designed topographic maps pleasing works of art. Vintage maps created by hand, even those outdated or inaccurate, can live on as wall decorations.