pgupta011 -- I fly most commonly these routes:
SFO - TPA (four times Sept-Dec), always UA
SFO - PHL or JFK (2X annually), always UA
SFO - to North America's Northwest (Seattle, Portland, Eugene or Vancouver) (circa 2/3 X annually), usually UA
SFO - various Pacific Mexican locations, always Alaska (UA doesn't fly to Zihua, Puerto Vallarta or Cabo (1X annually)
SFO to Hawaii (1/2X annually), always UA
SFO to LAX (3/4X annually); always UA
Sure, I likely could have accumulated UA miles more effectively earlier in the year but I didn't then know I had a hope of making PremEx because my elderly folks didn't get sickly until September . . .
I am gradually becoming more attached to the idea that it may make sense for some less-frequently flying FFs to maximize miles whenever it doesn't represent major inconvenience or additional cost . . .
I have consolidated as much flying as possible via UA which works well from SFO, except to Mexico. I regret not having joined Alaska's FF program years ago . . .