I'm rethinking the Frontier miles more positively in light of experience with Spirit. Spirit has the super-teasy RTs as low as 5K miles if you're a cardholder (and you might get a lot of that from card spend alone) BUT they're only good maybe one-third of the year (lowest off-peak times) and availability is sometimes tough.

The times you can use the reduced miles also happen to be the very same times they have to do their lowest rock-bottom fares. Did a $46 RT to TPA last weekend that included a 2.5K mile bonus and an opportunity to get 1K Avis miles on a $25.50 car rent. Maybe I should have planned ahead to go to CUN on miles instead.

YMMV but with F9 miles the award levels are higher, but much more of the year is covered. Also, from ATL their non-stops often get sales, but connections (e.g. places like PDX and BIS) tend to be much less of a deal and are good possible uses for awards.

Sometimes the F9 award flight is effectively a positioning flight to the other side of the country. Just did an Alaska trip that cost 12.5K DL miles, a $81 OW on JetBlue and 10K F9 miles, all to sidestep availability or mileage-needed obstacles. It was a bit of a kludge, but I got the dates I wanted (weekend after Labor Day) even though it took a toolbox to do it. F9 awards also could come in handy for positioning flights to a west-coast gateway.

So I'm slowly warming up to them.