Planning speciality selection question

Greetings,

I've been reading the boards here for some time, but never felt compelled to register until now. I'm a second-year student in a Master's Planning program at a school that gets to remain nameless (since I'm fairly sure half the faculty are members here). I have always intended to go on to a PhD program but lately I've been having trouble defining my area of interest between Econ. Development and Transportation, if only because I fail to see how the two are not so well-linked. I realize that I need to whittle down my study area and would like to do so while keeping in mind the following items that have been running through my head:

as I look at programs I am considering both Planning and Geography departments;
I would like to devote my time and energy to a speciality that offers the most career opportunities--in professional practice and academia;

I have a head full of interests and intriguing (at least to me) research questions, so I don't feel like I'm "selling out" (as one professor put it) by considering the above. I would appreciate any guidance that you all can give in regards to industry outlook, demand, university recommendations (I would like a program in the Great Lakes/Midwest region for a great many reasons), or any advice you feel is worth giving. Thanks for your time!