I don't know if I'd call this a "sweet spot" but on a few routes where the cash price was ridiculously high, I've found more reasonable points deals. For instance, one-way flights HND-ATL were selling for over $8,000 and the award price was 185K points. Note that this route usually sells for about 350k points (still a deal compared to the cash price), but for some reason the award price dropped for a few days before going back up and I was able to rebook the award at the lower rate.