The most elaborate and beautiful bedroom and bathroom in the home is usually part of the master suite. Often it has the best views and sometimes other rooms connected within the suite. That makes sense considering the people who sleep there own the home. We have designed wet bars, home offices, as well as terraces and screened porches off the master bedroom.
In my house the master bedroom is a place where kids congregate first thing in the morning and just before bedtime. A hazard associated with a great master bathroom(or at least the best bathroom in the house) is that everyone else uses it, thereby leaving the masters to wait their turn in the family line.
A master suite does not have to be huge, but it should be special. What makes that master suite special depends entirely on the people sleeping there.