Most of them here in Phoenix also sell gasoline. I generally save $0.07 - $0.12 a gallon on gas and there is a location near me, so I don't have to drive around to get a good price. I save $25-$30 a year just on gasoline.
I also buy large sacks of flour and sugar there, the regular price is a little lower than Smart & Final, but, occasionally, S&F has a baking supply sale that beats them.