Here in missouri, most gas stations provide 87,89, and 91. 91 being premium and 87 being regular.
I've taken a few trips around the state, and used some of the different gasoline for my car. I've noticed that in the more metropolitan areas, the 87 is fine and will yield close to 400miles a tank with 60/40 hwy/city driving. In the more rural areas, i found the the 87 to be trash, remembering a trip from southern Missouri up to Columbia to give me only 330miles on the tank, even though it was 70/30 hwy/city. (granted, my comparisons are using most likely some summer and winter blends)
Then however, i came across a gem of a gas station. A shell ~6 miles away from me sells 91 no eth (premium no eth), and if I don't get 400miles out of a tank, or at least close to it, i know i'm doing something wrong, and that's not exclusive to 60/40 hwy/cty, it ranges 40-60/60-40.
What i'm trying to say is, if you have access to no ethanol gasoline (most of the times it will be sold as premium), go for it.