In 2005, Backpacker Magazine selected 10 day hikes as America's hardest.  They all are over  8,000 vert ft and span amazing terrain.  From the article, the 10 are ranked as follows:
 1. Timberline Trail Mt. Hood, OR
Score: 95 Miles: 41  Elevation Change: 12,000 feet X Factor: Insane mileage 
 2. Pemi Loop, White Mountains, NH
Score: 92 Miles: 32 Elevation Change: 18,000 feet  X Factor: Knee-hammering rocks 
 3. Great Range Traverse , Adirondacks, NY
Score:  90 Miles: 25 Elevation Change: 17,600 feet X Factor: Endless ups and downs 
 4. Windom Peak, San Juan Mountains, CO
Score: 85 Miles: 20 Elevation Change: 11,600 feet X Factor: Violent thunderstorms 
 
 5. Cactus to Clouds Trail Mt.,  San Jacinto from Palm Springs, CA
Score: 80 Miles: 23 Elevation Change: 13,400 feet  X Factor: Broiling temps 
 6. Great Smoky Mountains End-to-End TN/NC
Score: 78 Miles: 32 Elevation Change: 12,300 feet X Factor: Mud, bugs, humidity 
 
 7. Grand Canyon South Rim to North Rim AZ
Score: 74 Miles: 21 Elevation Change: 10,500 feet  X Factor: Dehydrating heat 
 8. Enchantment Lakes Traverse , Cascade Range, WA
Score: 71 Miles: 18 Elevation Change: 11,000 feet  X Factor: Sketchy footing up high 
 9. Paintbrush Canyon-Cascade , Canyon Loop Grand Teton National Park, WY 
Score: 66 Miles: 19 Elevation Change: 8,000 feet  X Factor: The occasional ultramarathoner passing you 
 10. Bigelow Range Traverse, ME
Score: 64 Miles: 17 Elevation Change: 10,000 feet X Factor: Black flies with attitude