I decided to take advantage of UA's $338 SEA-LHR fare to spend a few days in London next week. Since this fare isn't upgradable, I decided to connect in IAD on the way there so that I could upgrade at least that portion of the long journey. On the way back I decided to fly through SFO just for variety, and I figured if I really hated coach on the 777 I could pay the difference in dollars ($300) to make the return a B fare which can be upgraded one way for 10K miles.

My question for 1K transatlantic travelers is this: is there a likelihood that UA will bump me to business class on one or both of the transatlantic segments? My brother is only a Premier, and he typically gets upgraded from coach to business on about half of his segments on transpacific flights.

Any experience or advice? Thanks!