I'm not so enthralled by those numbers (though, your math is correct). Back when the C award was 90k and F was 120k (1 year ago), it sort of made sense.

However, one year on, I can't be bothered to think about going out of my way to give UA money just to keep well pumping.

I recently advised all of my friends that fly international Y frequently to pitch their bosses on the idea of reimbursing them for FF redemptions based on lowest available fares. 3 of 10 bosses went for it, and now these folks are loaded with US miles going into 2010. While they won't earn status miles on their flights, they will be in C or F most of the time. Availability isn't as bad as some make it out to be. The drawbacks to this road are that change/cancelation penalties are steep.

ETA: I feel compelled to clarify my miles buying advice as a precautionary measure for those that could be inclined to overdo it, so here are the basics:
-US miles are currently a bargain until the end of the year, both using the transfer/purchase system (~1.2 cpm) and the 250% shopping bonus (~.72 cpm)
-the window on the latter may already be closed because transactions are supposed to post by 12/31
-US miles are superior to UA miles for trips to Europe and Asia for two reasons: 1) no Starnet filtering; and 2) lower award levels in C/F
-on the downside, US charges close-in booking fees and their tickets are very inflexible once booked
-if I had a boss willing to reimburse based on eco fares and 5-6 Asia trips planned, I'd probably buy enough miles to cover 3 trips in C or F
-for the remaining 2-3 trips, I'd try my best to use other miles that I'd accumulated
-I'd also make sure to have status in a program that would benefit me the one or two times that I had to cross the Pacific on a revenue fare