Niznick, a Las Vegas multimillionaire with few ties to Connecticut, isn’t just a dreamer with a grand vision. Since 2010, he’s already invested $25 million of his own money to renovate and rebrand the former Clarion Hotel at 42 Century Drive into a 141-room DoubleTree by Hilton. He plans to invest another $20 million to $25 million to build the event center and a second, 82-room Home2 Suites by Hilton hotel, which is a newer, modern extended-stay brand. The hotel would connect to the event center and current DoubleTree hotel. There would also be a 400-space underground parking garage.