I have redeemed the certificate before but after talking with my colleagues, I realized that getting those certificates is indeed a poor choice.

For those $25 off gift certificates, they are each for $10 on restaurant.com. However, usually there will be promotions and you can actually get one for $2!!! Starting from Christmas up until this point, I have seen at least 3 of such promotions going on!!! I frequently receive emails from them and now I have figured out how to get the certs I want.

To the OP: yes, you will need to diligently wait for the certs to become available again. It happened to me too. But once they are available, I get as many as I need. You can sign up on their website so that you will receive an email saying that new certs are loaded to the system.

Even if you can get the certs, note a few things:
1) It usually requires minimum purchase. For $25 certs, I have seen minimum as low as $25 and as high as $90!!!
2) Sometimes in the terms and conditions it will say that alcoholic beverage purchases is up to the discretion of the restaurant.
3) $25 is usually for dinner and $10 is usually for lunch. Check the T&C first.
4) Usually you cannot use those certs on weekends. Check the T&C.
5) 18% pre-discount gratuity is added to your bill, as specified by the T&C. Tip more only when the provided service is fabulous.
6) Some certs require a party of 2 or more. Check the T&C.

Enjoy!