Like others have said, it depends on you. While there are some nice places to use it at, if you are not planning a decent stay at any of them, it can be tough. Sure you can get a good value at a place like Bora Bora. Let's not forget that it's still very expensive to get there, and you would probably want to do more that one day. If you were already planning a trip there, it makes perfect sense to use. If you can find availability.
I also used mine at the Venetian. It was a $500 Saturday night room. Sure I could have gotten "more value" out of it elsewhere, but I wasn't going anywhere else that would justify it better.
Getting the absolute most of out these certificates is one of the main reasons they won't be worth as much anymore.