Yes, I have to agree with ozstamps. Not living in the US means not having good chances for upgrades, from Singapore every flight is international. Then upgrading with miles makes them much better spent. US$ 1000 flies you economy to Europe or US from here. 60 000 miles upgrades you both ways. Those Business class tickets cost US$ 4000 and above. 60 000/3000 is 0.20 cents per mile.
I am not claiming that this is the true value of a mile, but it does amount to better spent miles for me. On top of that, upgrade tickets still count on your milage ticker (WP gives me 30 000 for an intercont trip) reducing the cost to 30 000 for the upgrade)