I think (although many who do inexpensive multi-sector runs would disagree) that Qantas has a very good way of rewarding its top $ earning FF's and not its most frequent flyers.

Basically they have a system whereby you get Teir credits for each flight. They are basically:

0-1000 miles 10 point in Discount Economy, 20 points in Full Economy, 30 Points in Business etc.

You then need 350 credit to get to level one, 700 to level two and 1400 to level three.

The good side is a return first class flight from USA to Europe will net level one with ONE RETURN FLIGHT (bare in mind this makes the airline over $8,000 in revenue).

They have worked it out that you need to spend about $10 - $15 per status credit so Level One earns them about $3500 - $5250, level two earns them $7000 - $10500, level three $14,000 plus.

This allows them to really offer a great level of service based on your spend with the airline. Also when you get 7000 or 14000 credits ($70,000 - $95,000 or $140,000 above) in spend they give you Lv 1 or Lv 2 status for life.

I think this is the way that airlines need to go in order to gauge who are the "real spenders". While some loopholes are in the system generally you need to spend over $7 to get a status credit and as such any Qantas staff know that a level 3 (or Platinum) FF earns at least $14,000 per year for the airline and can be treated as such.

The end result is that a Platinum FF does get better service from the airline as the agents dont have to worry if this FF got his status by making deeply discounted trips or full F, C and Y flights.

Anyway just my 2c worth

NB: All amounts are in AUD but it gives you the idea!