Other Car Rental Programs/Partners (ie. Alamo, Enterprise, Sixt) - Upgrade vouchers

Does anyone have experience with using the upgrade voucher from http://www.americancasinoguide.com/Travel/alamo.shtml ?? Is it accepted printed and with the two sides on different pieces of paper? And will they accept it on a Holiday Autos rental at FLL?

Any other sources for upgrade vouchers? I have them for Avis, Hertz, Budget... so of course the booking turned up with Alamo

Has anyone had luck using the coupons from this post ? Specifically in LIH ? I booked a midsize car at $146 with the coupon and discount which is about half the other car rental company rates. I am concerned because last year I had trouble with Alamo in LIH accepting my Costco coupons. See http://www.flyertalk.com/forum/showthread.php?t=314910.

Alan