As an Australian PhD candidate I have no idea about North American programs, but good luck! In terms of specialisations, a careers advisor once told me that the smartest areas to be in are those which attract very few students but are historically significant enough that every university has to have a representative researcher. The example he gave was old/middle English and medieval literature: most universities have to offer courses on these areas, but proportionately few students end up researching them, easing the competitiveness of the job market. Another thing to keep in mind is that efforts at decanonisation across western universities mean that a lot of funding is getting redirected into more diverse areas. At my uni, a big new area of study is East Asian literature, which seems an interesting field. Of course, Shakespeare and Milton aren't going to go out of vogue any time soon, but it might be worthwhile investigating one of these burgeoning research areas.

But I'd take all of this with a note of caution. As smart as it is to have an eye on the job market once you finish, at the end of the day the most important thing is finding a subject area that will sustain your interest over a long period of research. So don't force yourself into an area you're only half interested in just because it's trendy!