Call (do not email) and speak with the sales manager directly. It is all about revenue and everything is negotiable.

Hospitality suite, meals, local transportation? If all you are doing is providing a recommendation to your guests and suggesting that they may want to stay at a given property, there may well not be a discount at all.

On the other hand, if you guarantee the rooms, maybe you get more.

For 40 rooms, it's going to be a pretty much set menu.