I can't believe you were upgraded even once on this flight. I took 348 last Sunday and as a plat on a mid-range fare was higher than 20 on the wait list after F boarded full. Personally, I wouldn't spend too much time changing your schedule around just for an upgrade because the upgrade is very unlikely to happen on any SFO-EWR or vice versa. Just make sure you have an exit row and treat any upgrade like a rare international op up - an unexpected but pleasant surprise.