Very well said FF24.

I want to add two things to that though.

1) Having a company stand behind you when there are problems is one of the most important benefits of the upper tier. When the plane breaks, or the weather deteriorates Delta has been awesome and always gotten me there.

2) As primarily an international passenger, the seat - most notably the quality of sleep in it is also a very important consideration.

When Delta ceases to be the best airline on the ground is when I'll look at making one of the others my first choice.