The raises/promotions/better job/ came while she was working toward the degree. This was twenty years ago. It is a changing world today. One could go for a Grad Certificate.
Definitely get it. Two fold, 1.) Your masters will likely have a "Project" or thesis depending on the focus. 2.) It will be much cheaper than getting it later, even if you can get tution through employer.
I always thought that the masters reuired X number of hours beyond the BS. At least mine did. I have a BS in Computer Science and a Masters in Software Engineering, i would not trade the experienc at all.