This is based on USAir experience, but I think it's pretty universal.

I've been on FT almost a year. I've learned a lot, and still finding out more.

There's no such thing as just "a ticket" - every ticket has a fare class, rules, etc.

There are the real el cheapos - e-savers, internet specials, etc. Typically limited availability, heavy restrictions. On a trip US-London, maybe $300-$350

The ordinary cheapos (US "V" class) is a bit more expenseve, but available continuously. Typically not upgradeable. Maybe $400-$450.

Then come the more desirable classes (US "K", "H", ec.). Upgradeable from "day of" to 7 days out (platinum). Maybe $500-$550.

There's another cheap class (US "B")which is upgradeable on the spot. Maybe $ 600.

Was booking a flight for myself and my wife to London. I have some SWUs and wanted to use them up. The res agent led me through some fares, and was able to locate a "B" fare for us. Cool. Then I asked about my SIL - could she buy the same ticket and maybe I could upgrade her with my miles? Sure. 10K per leg.

That's when the light went on.

I have a choice of buying award seats (80K for biz class) or buying a "B" fare and upgrading with miles (20K).

It strikes me that this is probably the most efficient use I can make of my miles. I can probably come up with an amount like $600 once or twice a year and dump in some miles for the upgrade - I even get miles for the trip (in my case, 100% bonus, so with 3500 miles one way I would bag 14000 miles, for a net cost of only 6000 miles). I could stretch my miles almost forever this way.

Am I going down the wrong road, or am I just learning something that everyone else thinks is too obvious to mention?

I mean, we all like "free", but completely free (award) will drain my balance a whole lot faster than mileage upgrades.

Enquiring minds want to know.