What is the coolest thing you ever seen from a plane? You guys ever identify any big cities or anything else from a long flight?
I've seen too many interesting things to mention, but I'll narrow it down *some*.
While not particularly visually interestng, I flew over the North Pole on a DC-Beijing flight. Same flight took me over a cloudless Greenland which is spectacular, as well as Lake Baikal, Russia. 20% of all liquid fresh (not salted) water on Earth is in that single lake.
Saw a lot of huge fires in the Sahara over Libya (London-Nairobi, Kenya flight) which were reflecting off of what must have been enormous sand dunes. Don't know if that was from oil production or nomads.
Volcanoes are very interesting from the air. Best I've seen include central America, eastern Siberia, Philippines and the Cascades. I've buzzed the top of Mt. Rainer several times on the way out of Seattle. Lots of other mountain ranges have been really amazing too. Among those, Alaska Range, Alps, Pyrenees and Andes in Patagonia (google Mt. Fitzroy, if your unfamiliar).
Saw the northern lights over Lake Winnipeg, Manitoba, though they look better from the ground, IMO.
Lightning storms, particularly cloud-to-cloud strikes at night are spectacular. Best I've seen were near Gabon on a Cape Town, South Africa to Dakkar, Senegal flight.
I flew into Bangkok in a single engine plane. Looking out the cockpit windshield at the super massive runway with all of the skid marks from planes landing was amazing. On an Invercargill to Stewart Island, New Zealand flight, the puddle jumper I was on was flying at an angle of about 45 degrees with respect to the forward direction due to strong winds. That was pretty cool.
You mentioned cities, and they are interesting. San Francisco peninsula and surrounding Bay Area is beautiful from the air. The outline of Manhattan Island from 7 miles above is interesting. The Gateway Arch clearly stands out when flying over St. Louis. The most interesting city experience I had was a San Francisco to Shanghai flight. It was overcast all the way across the Pacific. The clouds suddenly parted over Hiroshima, Japan. I know enough about that city to have spotted the park which exists at the center of the atomic bomb blast. After that, it went back to overcast. Amazing stuff.
There's a lot more that'll probably come to me. I've flown a lot - I love traveling.