Write a press release about your new spa and create a press kit and send to important local and national media. Attempt to call the editors to see how you can help them with your expertise. Think of who would be the most important people you would want to come to this event and what would it take to get them there. Plan that event. Come up with a party concept that would communicate what you are up to. More important editors may prefer a one on one visit. It is good to know the media and inviting them to your spa is a good way to start to know them. I think you are only new once so you should take advantage of that and get all the free publicity that you can.
If you can afford to advertise...great.