Yes, I am able to relax and enjoy the vacation. What works for me is to live in the moment knowing that I can handle whatever happens. Each night or each morning while having a cup of coffee I go over the plans for that day. Then I go with the flow. I do not micromanage. I really only manage transportation. I loosely manage timing so that we are where we want to be close to the time events start. I'm willing to change if what I've planned ahead of time with the family isn't working.
Over the years of experience i've learned that everything does work out OK. I was a chaperone for high school kids traveling from Oregon to D.C. by way of Boston and Cleveland. Because I was responsible, along with 2 other adults, for 40 teens I did have to stay on my toes. Even with the unplanned incidents that go along with family and these teens I enjoyed every trip.
With the teens, we had a written agenda with which we could be somewhat flexible. Because there were 3 chaperones one of us could manage a situation that involved one or a few teens while the others continued to stay with the schedule. We also spelled each other at times so that each of us could have alone time.
I suggest that you share responsibility with your husband and in-laws. Talk together about the next day so that you can let go for a few hours. Know that the success of the trip does not depend onLy on you. Accept the imperfections as they arise. On the extensive trip we often had one person stand in line for tickets or to gain entrance while the other two entertained the kids near by.
Yes, I was anxious, especially on the first trip, but I had a good time by being aware of my own needs and taking care of myself as well as the students. I learned to focus on what is happening now and leaving planning for the evening. I remember getting up early to get a prescription for one student who had an intestinal upset. I had stayed up late waiting for the hotel doctor to come to her room. The other adults managed most of that day without me.
Share the responsibility. Accept that there will be glitches and that's OK. Find ways along the way to have fun experiences for yourself. If taking a few hours away from everyone else will help do that.
This will get easier with experience. Seeing the space center is a great experience for all of you. I'd go in a minute even when young and inexperienced. I would've been anxious and I would expect a good time for myself as well as the kids.