As it’s nearly impossible to provide a flawless service, companies should focus their efforts on having one (or a few) very pleasant, memorable high points in their service, and making the last experience outstanding. These experiences will be remembered the most, not the sum of the experience.
This phenomenon is called the peak-end rule, Wikipedia defines it likes this: “We judge our past experiences almost entirely on how they were at their peak (pleasant or unpleasant) and how they ended. Other information is not lost, but it is not used. This includes net pleasantness or unpleasantness and how long the experience lasted.”
This works the same way for vacations.