SWUs for international flights. Especially if you buy them on eBay for $200. A cheap coach international fare + a $200 SWU puts you in United Business, which is sometimes better than best-carrier coach. (honestly, I'd prefer CX Economy to UA business on most routes, but UA wins for SFO-IAD-KWI.)
United business between Edinburgh and Newark means seats that fold down into beds and was entirely worth the US$480 I paid to upgrade my flight home last month.
They also have a monopoly on direct flights to the US from Edinburgh, which is another reason someone might end up on a United flight.
