Well, the currencies are all unique...personally, I think the SPG cost for direct purchase is quite good - I usually get about that or better in terms of value from hotel awards. (Probably why it's capped annually.) Hertz at 20 cents per point can be a decent value if you're a few points short of an award.

But probably not a great value being 800 points short of an award. For 2,000 points, you're just talking about a regular car - probably best to just pay the going rate for it or Priceline it. Or use the two free days and pay for two.

I typically use my Hertz points for standalone one-day rentals in high cost markets.