I submit that, and these are my values, you are wrapping your decision around the wrong things. First time? Maybe not again? If it were I, I'd do both. They're both very nice. Each has its own very worthy attributes, DSUs aside. The Grand: its club and breakfast choices. The Regency: its location. But this isn't to say that the other is bad in either (any!) respect. Both: super views of the harbour and laser show. And they aren't far apart geographically for getting from one to the other.

Grand, two nights to experience the restaurant and club buffets; Regency, one. Your trip will be so much more, imo.