You might want to explain the how you value a mile part a little bit more clearly. I've tried explaining it to my friend that loves to collect AS miles, but he still doesn't get it. He buys all kinds of stuff based on the email promos they send him (like 100 miles for buying flowers, etc) that he otherwise wouldn't because "he really wants the miles".
The simplest way to think about it is to consider what you typically use your reward for. I typically use mine for short trips on the PEK-NRT corridor, which often prices out at about $500 USD. What would I pay if I didn't use the miles on this? Well, I'd probably only fly it often if it were around $250 USD. So I get $250 of "value" out of the ticket. Take the 25,000 miles, divide by the value you are getting ($250), and viola, you get 1 cent per mile of value (not the miles forgone).
Another discount factor that you forgot to mention is the cost of capacity controlled rewards. If you can only fly on certain carriers on certain dates on certain routings, that's a "cost" that ought to be factored into the valuation. On the NRT-PEK route, there isn't much cost because getting a Y award is trivial with options on three different carriers that are almost never *Net filtered. However, if one's main goal is to use miles for leisure travel in C with a companion, UA miles are worth substantially less. Having to pick inconvenient dates, extra time in transit, using non-preferred carriers lowers the "value" side of the equation substantially.