Several achievements require visiting every "named location":
What are the named locations in Three Horns, Tundra Express, Frostburn Canyon, Sanctuary, Opportunity, Lynchwood, The Highlands, Thousand Cuts, Wildlife Exploitation Preserve, Eridium Blight, Arid Nexus, Sawtooth Cauldron, and any other places required for their five achievements ("Arctic Explorer", "Urban Explorer", "Highlands Explorer", "Blight Explorer", and "World Traveler")?
Are any easy to miss? Which? Is there any way to easily identify remaining named locations?