I would not make up an excuse... if it involves 'overtime', I'm definitely turning down vacation. It has happened before. I had a trip planned, purchased the plane ticket, I was going to do so many things in Hawaii (especially eat good food). Unfortunately, I was offered a job with better pay, it was a smooth transition from one job to another, only 2 days apart. What an experience. However, I did end up going on vacation, but only after my probationary period of 2 years... so I had to wait that long to take a vacation... ended up going to Delaware (its what was affordable). Rented a car & explored surrounding states, 'city-scaping' as I would like to call it. haha