Last month, we needed to get something done that involved communicate between Bosnia and Croatia.
Banja Luka was one of the destinations we needed to visit.
When we got there, our local partner recommended staying in Caldera Hotel. We were so tired and we could go wherever he recommended :) Without any expectations to find anything decent in this area (and the hotel is not in Banja Luka but on the way to the airport), we got there and we were really surprised by the offer and the quality.
To be honest, this kind of luxury and the service level - I don't see that often in Canada or USA. Room, spa, food, wine, stuff - everything was first class.

I usually don't write reviews on the Internet, but knowing how hard it can be to find a nice place to stay in some parts of the world, I found it could be useful.