Contracts with hotels for small blocks of rooms (say 20 rooms for 2 nights each) are generally fool's missions in my experience.

I've done them across all the big 3 chains and its far better to find/book on-line than negotiate with group sales - who must be compensated by commission. You would think volume discounts and add-ons (such as breakfast) would come easy in exchange for the guaranteed revenue but rarely do they offer anything you can't get better (or cheaper) on-line. When you call their bluff (why is your rate $20 more?), they get annoyed and tell you to just do that. And you get locked into cancellation / attrition penalties.

Much better off doing your thing on-line, then calling the GM with a rooming list and requests to be placed together.

I've also done the opposite where you pretty much take over the entire hotel. You get to dictate price but those contracts have various deadlines and limits as to how much you can give back so many days out.