If have one free night ( from IHG credit card) where to use?
 

The best I came up with the Venetian hotel in Las Vegas. Can you think of some other alternatives and adding additional point or pay nites would be fine.

It's a much better idea to use it where you want to visit, rather than listen to a bunch of random strangers on the internet. We have no idea if you prefer Vegas to Hawaii or Bora Bora or London or wherever...

True, thank you for guiding me to see this point.

I like the IC Hong Kong.

I have stayed there and also like it.

Best value are the expensive ICs such as Paris Le Grand, Amsterdam Amstel, Bora Bora either Thalasso or La Moana, Hong Kong, Willard, Boston, LA, New York Barclay, London Park Lane, Bordeaux Le Grand, Moscow, Geneva, Osaka, Kiev, Fiji, Moorea, Tahiti, Davos, etc.
The ones in the South Pacific can run over $1000/night; others can push $500/night or more. But agree it's more about where you want to go. Key for the free nights and also for point redemptions is to save using them for periods where a hotel might be very expensive and you can stay free.

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.