We just came back from our last Spring Break vacation with a high-schooler. Our dd is 18 also, and our youngest, and the event was indeed bittersweet.( Having to pay for a 3rd adult in the room was a downer, I'll admit.) Just enjoy having this time with her. The years speed by all too fast. Her older brothers would go to WDW in a heartbeat, (if dh and I were picking up the tab, lol)~my goal is to have the whole family there again at one time.