I have my master'sin chemical engineering. Im working on my PhD while working full time (hard to get full sleep).
For me, it is worth it. Having a master's was more or less the requirement for my job (I am employed by the Government), and having a PhD will allow me to advance further. However, that is because I am involved in managing research programs, and even doing in-house R&D. If it weren't for that, having a PhD wouldnt do me much good. That said, most companies that I interface with have a few PhDs that run the research and development programs. So, even in the private sector, it is important as a consideration for someone who can have an advanced professional degree, run their own research, and do their own thing.
A Master's degree is almost a requirement these days if you want to stand out, as the [censored] of today is little better than the high school diploma of yesteryear. Unless you have some other source of clout or recognition, you need stuff like this to differentiate. It does not mean that there arent lots of really smart and excellent [censored] or high school graduates, but from the typical working world angle everyone is the same until they stand out. You have to get your foot in the door before you can stand out, and if you ever want to apply for a grant or other infusion of cash, your credentials are important too.
There is always a balance too... a lot of jobs these days are looking for folks with experience. Having a master's can help offset some of the experience requirement. Then again, it is also possible to be overqualified, having too high of qualifications and being too experienced.
For someone wanting to do facilities, maintenance or operations management, having an MS is something that IMO is smart. Given that you will have a large number of folks under you, it helps to have an additional qualification that sets you on a higher pedestal. That said, unless you are doing highly technical or R&D type work, I dont think that a PhD will help you in your field.
Engineering management or something along those lines might be good.
JMH