BTW I'm not sure when the OP is traveling. But the 77A on SFO is only available daily between now and Mar 27 and then every Mo, Tu, Th, Sa between Mar 28 and Apr 30. After that there won't be any 77A on SFO until Oct 31. So if he/she is traveling on the days/dates mentioned then there will be a choice between the 74A and 77A. Otherwise they are all 74As.