North: Juneau, Alaska
South: Stewart Island, New Zealand
East: Jabalpur, India
West: Perth, Australia
Highest: Around 15,000 ft in the Peruvian Andes.
Lowest: About 100 ft below sea level on the Valdez Peninsula, Argentina
North: Amsterdam
South: Martinique
East: Vienna
West: Oahu, Hawaii
North: Glasgow, Scotland
South: Austin, TX (I might have been in Houston at some point as well, but I don’t remember it.)
East: Not exactly sure about this, but somewhere in England
West: Ruby Beach, WA
Highest: MacDonald Pass (Highway 12), between Garrison and Helena, MT. 6299 ft.
Lowest: Looks like I’ve never been appreciably below sea level, so I don’t have a good answer here.
North: Anchorage
West, South: Honolulu
East: Washington DC
Highest: Breckenridge, CO
Lowest: The beach
South: Zárate, Argentina.
North: Inverness, Scotland.
West: San Francisco, California.
East: Heraklio, Crete.
Highest: Aneto, in the Pyrinees.
Lowest: sea level.
North: Quesnel, BC
South: Grenada
East: Vienna
West: Kauai, Hawaii
I’ll be damned. Add up all the differences, and it’s probably not more than a couple hundred miles.
North: Trondheim, Norway (about 63° N)
South: Sarasota, LF (about 26° N)
East: Seoul, S. Korea (about 127° E)
West: Somewhere near the coast of Oregon, on rt. 101 (about 124° W)
Highest: Somewhere in the French or Italian alps, near Mon Blanc (about 3000, 3500 m?)
Lowest: Dead Sea, Israel (~-400 m).
North: Goeteborg (Gothenburg), Sweden around 57° 42′ North
South: Buenos Aires, Argentina around 34° 36′ South
East: Tokyo, Japan 139° 46′ East
West: Forks, Washington 124° 23′ West (never did go visit my sister in Kodiak at 152°)
The lowest would have been scuba diving somewhere, at least 100 feet below sea level. I live about 10 feet above sea level, so I’m a bottom dweller. For highest, I’ve been skiing atop several mountains, but too lazy to go back and figure which was the highest. At least 14,000 feet, but probably not much more than that.
Pretty unlikely - the Franz Josef Glacier is very low altitude - the bottom is only about 300 metres ASL, and even the highest accessible parts are not much more than 1500 metres - lower than Denver, say!
For me:
North: Nordkapp, Norway, about 71º10’N
South: Balclutha, New Zealand, about 46º15’S
East: Viti Levu, Fiji, about 178º33’E
West: Rarotonga, Cook Islands, about 159º49’W
Up: Point Lenana, Mt Kenya, 4985 metres (16,355ft)
Down: probably Schiphol airport, Amsterdam, which is apparently -3.4 metres (-11ft) Although having said that, the tidal range in Devon where my parents live can be as much as 10 metres, so I’ve probably been lower than that when swimming at low tide 
Edit - or I suppose I could count the Channel Tunnel, which goes about 115 metres (377ft) below sea level. But that might be cheating…
Home: Midland, Michigan USA - 43 38 N, 84 11 W
North: Barton-upon Humber, England - 53 41 N, 0 26 W
South: Buenos Aires, Argentina 34 36 S, 58 22 E
East: Munich, Germany- 48 08 N, 11 34 E
West: Bangkok, Thailand - 13 43 N, 100 28 E
Up: La Paz, Bolivia - 12,000 ft (3360 m)
Down: Swimming in the ocean - 0 ft / m
I used to travel a lot for business, and it was tiring but very interesting. I miss it sometimes.
Home town: Kaukauna, WI
North: Copper Harbor, MI
East / South: Sarasota, FL
West: Eureka, CA
Elevation High: Pikes Peak, CO
Elevation Low: Sea Level
Brian
North: Amsterdam, Netherlands (which is barely north of Moosonee, Ontario…this blows my mind)
South: Hollywood, Florida
West: Los Angeles, California
East: Athens, Greece
North: Montreal
South: Curacao
East: Bermuda
West: Honolulu
North and East: Helsinki, Finland.
South: Julia Pfeiffer Burns State Park, California.
West: Tofino, British Columbia.
Northernmost: Glacier, Montana
Southernmost: Orlando, Florida
Easternmost: Boston, MA
Westernmost: San Francisco, CA.
Highest: Pike’s Peak (14,110 feet).
Lowest: Sea Level: Cape Hatteras, Gulf coast, etc.
North: not quite to the Arctic Circle, on the highway north from Fairbanks, Alaska
South: Cabo San Lucas, Baja California
East: the island of Rhodes
West: Somewhere in the wilds of Alaska, west of Anchorage
High: Pike’s Peak, probably
Low: Death Valley, Ca
West: Cornwall, UK or Brest, France - not sure exactly.
North: Copenhagen, Denmark
East: Malmo, Sweden.
South: Marseille, France.
Highest/Lowest: No idea. I live in the Netherlands, so I’m below sea level quite a lot of the time…
I need to get out more.
Actually, I went to Napoli, Italy decades ago: so that’s my outer east/south point.
North: Fairbanks, Alaska
South: Curacao, Netherlands Antilles
East: Aalten, Gelderland, Netherlands
West: Sterling, Alaska
Pretty mundane…
North: Anchorage, Alaska
South: Durban, South Africa
West: Kauai, Hawaii
East: Tokyo, Japan
Lowest: Death Valley, CA
Highest: Quito, Ecuador (2850m)