You need another choice. I carry mogas to the hangar and use it for filling prior to a flight. But on a trip I will use either when needed and won't go far out of my way to find mogas on a cross-country. But so far I have only used 5 gal of 100LL.
Ditto with Bill's comments. I will use 100ll if the trip is more than two hours one way as I have never found 91 octane at any airports. I dislike using the 100ll intensly as it requires oil change etc etc etc. 90 octane I have found, but don't use it.
Dick Seiders
Curious how many of the hi octane mogas people are ethanol free or ethanol bound. Only problem I've found using occasional avgas is that you have lead in your system for a very long time...long after several oil changes. It diminishes...slowly.