I'd say the best I've done is the 200 point (250 - 50) off-peak weekend rentals. I used two of those to get about $70 off a rental, or $.175 per point. I don't accumulate enough points to turn in 5,000 at a time.

I think we get into the same discussion here that people hit with airline tickets -- do you compare the points to a premium seat you wouldn't pay for or to something that you were going to pay for anyway and got complimentary. The credit I noted above is one I would have paid for without the certs, whereas the $3,200 for an H2 noted above is something I would only redeem for.