And one of those LCCs (that has lots of flights to various places from Houston) doesn't use miles, but rather credits which are based on the number of flights, not the length of them, and gives you a free UNRESTRICTED (last minute) ticket for about every 5.3 flights (less if you also earn credits through rental cars, hotel stays, etc). The one downside is that Southwest's credits expire 12 months after you use them, so it only works if you either fly them enough or use partners enough to get 16 credits (what you need for that free flight award) within 12 months.

And then value of a credit depends a lot on whether you're likely to have a last-minute use for it or not. If you do, 16 credits is $600ish for longer flights, and that works out to around $37.50 per credit or $18.75 per half-credit. The half-credit value is useful because the MINIMUM they give for partners is a half credit, in situations like rental cars where other airlines give only 50 miles per day or Hampton Inn hotels where other airlines only give 100 miles per stay (and I doubt you can even attribute a whole SINGLE DOLLAR to the value of those 50 or 100 miles!). And even if you don't use the ticket that way, the value of a half credit is likely to still be lots more than the value of 50 or 100 miles.

But again, if you don't amass 16 Rapid Rewards credits in a year, you've got ZERO value. So depending on your situation it's likely to have either by far the highest value for all-coach domestic flying of any Frequent Flyer program, or no value at all. (Hard to think of a situation for all-coach where it would have some value, but significantly less than the mileage-based airlines, at least for some one based in a Southwest city like Houston.)