Just thought I would update on this in case anyone else decides to obtain these from Airmiles. Although it says Alamo Rent-A-Car Certificate, it is NOT like $100 certificate you use at Sears or anywhere else. We had major problems in Orlando with this - which I am writing both Alamo and AirMiles about -
Basically we obtained these $100 US certificates from Airmiles. Got two of them because it said you could use 2 per reservation. However, we get to the airport and they won't let us use them because we "already got too good a rate on our SUV"

So basically, I had done my homework, got codes and rates off mousesavers and then she doesn't want to let us use the coupons. DH was furious. She said we had to call Alamo and get a new reservation - "but you won't get that good a rate" (which is logical because I kept checking the rates to book a good rate and just showing up most likely would not be the best. Anyway. Called Alamo and (they were much nicer than the lady in Orlando at MCO) they told me I could apply one certificate as a coupon on my exisiting reservation, so they did that and basically I got $100 off our rate (which included my mousesaver codes etc.) So, now I have a $100 coupon which expires next March because I could only use one, contrary to what it says on the coupon and on the airmiles website.
I really feel Air Miles was deceptive in the way they advertised this. Alamo also could have made the certificate a heck of a lot clearer. It just says on the cerficiate at the front - coupon code.
So -- a word of warning. Obviously not a lot of people use this since I did not get a response the first time.
One additional point. No line up at Alamo at all. Then when we went back to the counter - a different lady MUCH NICER just directed us to the automatic machines. We handed in our coupon and paper at the garage.
TONS of vehicles to choose from. We took a GMC Envoy - leather interior. Quite nice. There was also a Rendevouz with leather and third row seats but it had some dings on it already and after our first hassle did not want us to be blamed for that later so we did not take it.
Deb