Rooms in convention centers (e.g., Whitehall) do not have venue-rental fees. For Wishes weddings, there are no venue-specific food and beverage minimums either - just the $75/$100/$125 per person that you have to meet no matter where you hold your reception.
Escape weddings that hold catered receptions at the convention centers are a little different. You are given a venue-specific food and beverage minimum that varies according to season, day of the week, group size, etc. So you'd have to ask your planner what the minimum is for your event.