Add one more factor into the P/S mix:

Just because a hotel is listed with a Point Stetcher period, this does not mean that award nights are necessarily available at the Point Stretcher rate. Even as a Diamond I was unable to get the advertised Point Stretcher rate at the London Waldorf Hilton for two nights in the beginning of September.

But IMO the best use of HH points is for "Big Time" awards like the Safari or GLON/GLONP awards. The per-night rates for more minor awards - particularly in the US - are frequently too high to be of practical value.