Per this FlyerTalk thread, Hyatt was going to stop selling their Stay Certificates yesterday, January 7, 2014. However, for those of you who meant to purchase one of these certificates and totally forgot, they are still available.
I wrote more about these certificates last week, but essentially they fixed certificates that come at 5 different levels. You can check this site to see which certificate level you need at each participating hotel. These are capacity controlled, so even if there is a standard room available, that does not meet these certificates are available for redemption.
I personally have used them a few time, for example last summer for two nights in Newport, Rhode Island which ended up costing $202/night (the cost of the stay certificate, which also includes taxes), instead of paying the lowest rate of $300+/night. Not all hotels provided the best value, but there are definitely some gems where using a stay certificate was way cheaper.
Keep in mind that even though these stay certificates do not have an expiration date, all hotels will stop accepting these legacy certificates come April 30, 2015. If you have a no expiration date certificate, you ultimately will be able to exchange it for the new “Hyatt Night Certificates” that are replacing these stay certificates (and available only for corporate bulk purchases, not individual purchases) or a Hyatt gift card for the amount that was originally paid. The Hyatt Night Certificates do have expiration dates. The exchange program is not yet fully defined, but will be communicated out in more detail starting this April.