When I was looking at getting a Masters, I pretty much convinced myself that on-line was the way to go as I couldn't afford the sabbatical from my civilian job nor could I afford the time demand of a set class schedule.
I looked into AMU for a Masters in Military History, but at the time (late 90s) it was nationally accredited but not regionally accredited. Seems backward, but regional accreditation is really the one that matters. I believe they are regionally accredited now.
Norwich University has a fantastic Masters in Military History on-line, but it costs a lot.
I started taking classes on line via Sam Houston State University
www.shsu.edu through their Masters in Military History. I took three classes - one each semester, and I'll say they were the three most interactive courses I've ever had. One was on the Vietnam War, one was World War I, and one was on the history of Texas. The Vietnam course was taught by a Pulitzer Prize winner. Each class was taught by a professor who had written extensively on the subject. Each professor spent lots of time critiquing my book reviews, answering my questions, and engaging in conversations on and off topic.
I would have gladly continued with SHSU as the cost of tuition and textbooks was actually much less than the compensation through the Montgomery GI Bill for Reservists and what my civilian company paid for tuition assistance, but I had taken JPME I via the Naval War College seminar program, and the timing was perfect and I ended up getting a full Masters in Strategic Studies from NWC with the three electives from SHSU. Since I was (am) still in the Navy Reserve, the NWC degree was the better fit.
Regarding what it's worth financially, since I was working as a government contractor doing staff work for the DoD (specifically Joint Forces Command, Naval Warfare Development Center, and Fleet Forces Command), having JPME I and a Masters from the Naval War College enabled my company to bid me against more contracts we were pursuing which required that level of education and experience. For me, that directly translated to a $20k pay raise one year.
If you stay in the Navy, or in a military-focused career like gov't contractor, the name on the diploma matters less than the fact that you have the diploma. But, I am also aware that I will not be able to leverage the SHSU or NWC name for really big bucks like I would if I was a graduate of Wharton or Kellog Schools of Business, etc. However, considering the fact that I paid zero to get my Masters (other than four years of hard work, one class per semester), it has been a great return on my investment.
Quite frankly, you should consider doing this sooner than later. Cruise or IA deployment is a great opportunity to start as you really have much more free time on your hands than you are willing to admit. There never is a good time to do it, so you might as well suck it up and get started.