Let me clear up a few items;
The 763 has the lowest seat/mile cost. Period. However if you are able to fill a 777, then even though each seat costs more to fly, overall you get more profit because even though there is less profit per seat, you have more seats therefore more total profit per flight. And flying one 777 costs less than two 763's.
An airline can purchase the 763 for lowest seat/mile cost, but if you're only flying 100 passengers in a 250 passenger plane, you lose money. However if you put those 100 people in a 737NG, you make a profit despite each seat costing the airline a little more than a 763 seat would. That's why Aloha flies the 737-700 to smaller markets, and makes money on it.
As said above, it's all about what you can fill, and what you can pay for.
Also, North American Airlines flies 757's into HNL
) for a number of charter vacation companies.
One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.