You can tell my my screen name that once I did fly UA often. Now, there's no way I'd give up F9 for UA. I am happier as an F9 Ascent than I was as a UA Premier.
At UA, I ran a good chance of sitting in E-Minus, perhaps the worst coach class in the air, rather than being upgraded. So in return for just a chance to have some perks in the front of the plane, I will gladly take the uniformly friendly attitude I see from F9 employees who seem genuinely glad that I do business with their company, as well as the most comfortable domestic coach seat available.
As an aside to UA admirers who post here, don't try to convince alot of us who have departed UA to return, even if F9 doesn't go to Hawaii. You're happy, we're happy. Life is good.