You're pretty much correct in that with a revenue based redemption system, there aren't particular sweet spots that yield markedly better value than other redemptions - instead, it's much more like a direct rebate of roughly 1.5c per point. The highest actual value I've ever seen is 2.47c per point, on absurdly cheap flights with even more incredible points ratios. As critterlynn explained well in post 5, the highest values mostly have to do with what proportion of the cash fare is taxes and fees that are waived when booking with points. There is some variation in points:$ of base fare, but that also favors lower fares. Basically, if sometimes having cash tied up in Southwest travel funds (tied to a particular passenger) isn't a problem for you, then generally you'll want to book cheaper flights with points and more expensive flights with cash.

If you're the only truly frequent traveler out of the group, though, you'll probably do better just always using points when booking for your family. This is because points will return to you if your plans change and you have to cancel, or if prices drop and you refare. Cash fares will end up creating travel funds that are tied to the originally booked passenger, with a one year expiration date from the original booking. If you're trying for status, you'll probably do best to book your family on points and you on cash fares - theoretically you're flying often enough to make use of the travel funds if that's what you end up with.

Also, CP is amazing, especially when you can attain it through flights on someone else's dime. Doesn't change the points/$ valuation a bit, but sure saves your points or dollars if you fly with the same person frequently. Welcome to WN!