They will definitely offer the 80% before Christmas. They offer it every month, I have even gotten 90% off before.
Personally, I would never give these as a gift because they require money to be spend out of pocket. It may be a $25 gift certificate, but they have to spend at least $35, sometimes $45 before the certificate can be used.
I find them to be great discounts for me to use when I go out, but not for gift giving.
IMHO