It really does depend on your career goals but an MSW is a versatile degree. I've worked in family based therapy, been the director of an inpatient unit for substance abuse/MH, worked in outpatient substance abuse for the Army, worked private practice, and now I work at a VA providing psychotherapy. All of that was with my MSW and of course, LCSW. Keep in mind that different states have different acronyms for the license. Bottom line, you want to be independently licensed. This allows you to bill insurance companies once you get paneled. Be prepared though, this process (getting paneled, billing insurance) is not as straightforward as you may imagine.
First of all, not all insurance companies will panel with you (meaning you can't see those clients in private practice (PP) unless you don't want to get paid) until you have a certain amount of post-licensure experience. The big ones are Medicare, Tricare, and Medicaid. There are some others, but unless you get in with a well-established practice somewhere that generally gets a lot of referrals from good insurance sources, making money will be hard. Private practice is great but you will really want to be in with a group practice somewhere once you start. That will help with referrals, etc. As far as the work involved with being a therapist...it varies greatly depending on where you work. Keep in mind that in private practice, if your patient doesn't show, you don't make any money. This can be very difficult if you live in an area with common bad weather or aren't good at getting your patients to show. Many LCSW's get around this reality by working for the VA, DOD, or some other federal agency. They generally pay well, have good benefits, and you don't have to worry about the no show issue. That said, depending on where you work, your caseload can be HORRIBLE.
I work for the VA and my caseload is not manageable and is in fact, probably unethical. So, while I'm compensated well for my field, my days are generally very stressful. Back to your goal of marriage and family therapy. You could go the LMFT route, but you'd have a few problems there. There are a few insurances, and some of the big ones, that don't panel with LMFT's. The federal government also does not hire those folks. So, in my opinion, if you think that you'd never want to pursue a PhD, an MSW is a good option. I've never had trouble finding work and personally, I've always been compensated well enough for me. Just keep in mind the timeframe - 2 years to get MSW, at least 2 years to get LCSW with the possibility of having to pay someone out of pocket to provide your supervision hours, and 2-3 years after that until you're paneled with ALL of the major insurance companies (which requires paperwork, malpractice insurance, regular updating, etc). As far as field work, you will have to complete an internship. Mine was 32 hours per week. I was lucky enough to get in with a company where I already worked (a local hospital) and vary my day to day enough that we called it my internship. So, I was paid for mine. That's atypical though. Otherwise, it's very hard to work and do a program like that during the internship. If you have any questions, just ask!