In the Store: Before you get lured in by a unit's onscreen mapping abilities, make sure your home computer's operating system is compatible with the proprietary software.

A long battery life is key for multiday tripping in the backcountry, while a large, easy-to-read screen is indispensable for car or bike travel.

In the Field: Use a durable, rubberized case to protect your device from falls or getting crunched in a pack. Likewise, an IPX7 rating—indicating that the unit can be submerged in three feet of water for 30 minutes—ensures you won't have to baby your GPS in a storm.

At Home: Don't skimp on digital-mapping software. Expect to shell out about $100, but custom maps are worth it.