I <i><b>love</b></i> sunrises and sunsets. I once got up at 5:00 in the morning to take photos of the sunrise on the longest day of the year when I was staying at the beach in New Hampshire (and <i>boy</i>, was that water <i><b>COLD</b></i>!!!) I've taken photos of <i><b>lots</b></i> of sunrises and sunsets. But I don't think the realization of a Key West sunset can possibly live up to all the hype.
That being said, I know there are many people on this board who have very much enjoyed the sunset at Key West. <b>So...</b>, yes, you can see the sunset from the port (left) side of the Magic. The view would be just as good, if not better, than the view from the dock at Mallory Square, but you wouldn't have the carnival atmosphere that's offered at Mallory Square.