SFO is the hub through which I generally connect. Not doing less than a 2hr connection these days as at least 50% of morning flights and 100% of afternoon flights to SFO have been delayed. In addition, there is gate renovation, so there are (domestic) flights leaving from terminal A, which requires going through security again. That said, there are good lounges and I can think of a lot worse airports to need to spend time in. I just plan for up to an hour delay.