A masters is nice, but won't make you any more competitive. It might make you stand out a bit, but won't give you any significant advantage over another pilot. Your qualifications, including the aviation degree, are fairly cookie-cutter. That you're white or have a spouse in the military don't matter. Married doesn't mean anything. It did at one time, but that's long past.

Someone mentioned working as a FAAST counselor. Get involved in some volunteer work. Little league coach, scoutmaster, volunteer firefighter. Gives you something to talk about in the interview, makes you look more rounded, may make you a better human being.

Try other types of flying. A broad background isn't a bad thing. If you don't have any significant pilot in command experience, go get some. If you're stuck as a regional FO, then the regional may not be the best place for you. SIC experience is really only worth the time it takes if it's moving you toward a PIC position. If it's not, find something else to do.

If you happen to be one of those that jumped onto the regionals as a 300 hour wonder and have no PIC experience, you're better off going some place that you can get that; go fly freight, do something that gets you PIC time.

Get some maintenance experience. There aren't that many maintenance qualified aviators; it does make you stand out a bit, though it's not something you'll use a lot as an airline pilot, aside from being in a position to get a good handle on systems quickly.

Airlines may love safety but airlines don't love unions. Prior union experience, in my opinion, is not viewed favorably by most employers.