I don't see any mention of this so far, but one of Frontier's greatest perks to Summit members is that they waive all change fees. So you're free to make bookings far in advance for trips which "might" happen, change plans last minute, or even cancel trips entirely, and just use the credit for a future trip. The only downside is that you have to use the credit for a trip of the same or greater price, because you don't get a refund or remaining balance credit. I got around this by booking two one-way tickets (the same price as round-trip) for trips which I wasn't sure about, but wanted to lock-in the price at the 21-day point for maximum savings.

Edited to note: I am certainly not advocating abusing this by making purely speculative bookings, I only booked when I was reasonably certain that I was going, but it gave me the confidence that if my plans changed, I was in the clear. Along with the free confirmed same-day-change policy, being Summit allowed me to hop on earlier flights, decide to visit a different city last-minute, and generally live more in-the-moment than is possible for most flyers these days. I lost that status when I took a non-traveling job, but I'm hoping to keep Ascent this year.