Originally Posted by jsloan

1 - the number of miles needed depends upon the route, and, in some cases, the fare class. 30K is correct for North America to South Asia, discount economy to business.
2 - The upgrade covers both segments. If only IAD-SFO clears, you'll get a free refund. If only SFO-SIN clears, you'll get no refund at all. This is true because SFO-SIN is marketed as Polaris. For non-Polaris flights, the upgrade is considered used if any segment clears.

Note that IAD-SFO and SFO-SIN are both very difficult upgrades, as (a) they'll sell all of business class seats and (b) the upgrade list takes United status and class of service into account.