TPAC is FT shorthand for Trans-Pacific. (You'll see TATL around here a lot, too.) On an itin like this, when someone talks about the "TPAC segment" and specifically what airline is operating it, it's because we're mainly interested in the long-haul part, with the short regional/domestic connecting flights being a bit secondary.

SFO is San Francisco...a ton of Asian-bound flights go out of there. The "cheap" Orbitz routing I saw this morning was Cancun-Dallas-San Francisco-Beijing-Shanghai. One extra stop, about four extra hours, about $450 (I think) cheaper. But...just one-way...not part of the circle trip. Your total $2k fare is pretty good.

I've seen a lot around here about avoiding China Eastern. In general, the Chinese airlines aren't highly regarded like many of the other Asian carriers are.

I've only flown Eastern once and I didn't have a problem with them. But it was just a late-night PEK-SHA run, not long enough to care. It did illustrate to me how huge these two cities are, though. Flight was an old A330, packed to the gills, taking off at 9PM on a Wednesday night. And they were running something like 10 flights a day, all big planes, and I'm pretty sure either Air China or China Southern was doing the same thing. We joked about how the A330 and B767 were Chinese "regional jets".