Forgive me if one of you here was the creator of the earning miles idea, but at risk of being overly blunt, I think it's ridiculous.

One flies miles. But earning miles? Huh? Let me list the ways this doesn't make sense:

1. It's just awkward to have the same word refer to distinctly different things. "I flew 12,500 miles round trip to/from Europe, but I earned 25,000 miles because I get double RDM due to my 1K status (which is actually from flying not 1,000 miles, but 100,000 miles, er, 80,000 miles with bonuses). Now I can redeem those 25,000 miles for a 5,000 mile roundtrip next month." Anyone outside the travel-geek set would just find this nuts, IMHO.
2. As suggested in previous item, miles flown rarely equal miles earned. Bonuses, limitations, etc.
3. But wait, it sometimes gets even more confusing! Sometimes UA runs a special that lets you fly under, what is it, 1,500 miles for 20,000 miles? "So, honey, I just flew 10,000 miles but got 20,000 miles and I'm going to save 5,000 miles on a special promotion by booking an award for less than 1,500 miles..." aaaaagh!

So my two suggestions are these:

1. Why don't the airlines rename "miles," "points." Then you won't get the sort of confusion I've seen from non-frequent travelers, who assume banking "5,000 miles" means they can fly 5,000 miles for free. (okay, I know that is too good to be true, but really... why would you call them miles if you can't redeem them directly for, well, miles?) Additionally, it'd make a lot more sense outside the flying context. I bought $250 in groceries, I got... miles? No, points. I stayed in a hotel for a few nights, I got miles? (what, I jogged around the hotel?) No, points!
2. Simplify points!: (all one-way)
   - 100 point for short trips (e.g., SFO-LAX)
   - 300 points for medium-length trips (e.g., SFO-JFK)
   - 500 points for long hauls (e.g., SFO-AKL)
   - 100 bonus point for full-fare, business, or FC bookings.
   
   Want to redeem? (one way)
   - 1000 points for short trips
   - 3000 points for medium-length trips
   - 5000 points for long hauls
   Double for business (e.g., 2000 to fly a short haul in C)
   Triple for FC.

* * *

What do you think?
1) Would this be good for frequent travelers?
2) Savvy travelers?
3) Leisure, occasional travelers?
4) Business travelers?

I know, I know, there are also tons of issues about reciprocity, alliances, how to transition, etc. And for these reasons, I don't think it'd ever happen. But I think my proposal is a nice compromise between the very basic but not-very-flexible Southwest version (1 credit whether you fly from SFO to LA or NYC) and the complex/also inflexible UA/typical system (same "miles" needed to go SFO-DEN and SFO-JFK?!)

Another alternative which'd be simpler in a different way:
For every 100 miles you fly, you get to fly 10 miles (literally) for free. e.g., fly 25,000 miles, fly to any destination of 2,500 for free (or fly two trips of 1,250 miles, etc.). Hmm Then, at least, miles are somewhat sort of miles, eh?