It very much depends on what you would like to do. If your ultimate goal is research, then combined PharmD/PhD would be a better option. It would be extremely difficult to advance your career on the research side with PharmD alone.
For anything else, be it working on the medical side (medical communication, safety, as an MSL, etc.) or commercial side (marketing, market research, etc.) a PhD would not benefit you. I would rather suggest a fellowship in the area of your interest (they last one or two years, and you do get a decent stipend - I think they average between $40,000 and $60,000).
I think that going to a private school for the combined program at a significant added cost to you would not be beneficial unless you definitely knew that you want to be a researcher, and a researcher in a particular area. To get the full benefit of a PhD program you really need to have an idea about what you want to research, what would be the topic of your dissertation. I would rather go for a PharmD now, and then if you need a PhD later to achieve your goals, you can always obtain it later. There are even part-time PhD programs out there for people who are already employed in their area of interest, and generally if you are employed within a pharmaceutical industry, your education which is related to your job, even marginally, is either completely covered or at least 50% covered.