I'm going to need to rent a car on a number of occasions this year (in the UK, Puerto Rico and Hawaii) and I'm a member of these organizations which have some sort of affiliation with Hertz:

American Automobile Association (AAA) of New Jersey
Costco
Continental Airlines (not elite member but bog-standard OnePass member)
American Express (Gold Card)

From time to time I receive a leaflet or an e-mail with a discount code or upgrade offer from these various organizations.

Just wondering if anyone knows which of these listed above seem to be the most favourable for price or/and upgrade, or on the other hand are most of these offering basically the same 'benefits'?

(My spouse is a No.1 Hertz Gold member but I assume that I can't make any bookings using his card if he's not travelling with me?).

Thank you in advance for any suggestions