Cissia,
For your specific situation, I would be inclined to say that Harvard is not worth the money. You ultimately plan to get a PhD...so, if other programs (which are ranked *high* in your field) are offering you admission into their PhD program, then I would say that is the best option.
Getting a Masters from Harvard would only serve to help you get into a PhD program...so unless your dream is to get a PhD from Harvard specifically, then it sounds as though getting your Masters won't do you too much good (at least not 80K worth).
UWash is a fantastic school for public health, as are many others. There does not seem to be a huge gap in opportunities for those attending top ~10 PH schools. I would ask both programs about their alumni and compare where they end up.
Also, when trying to decide, location may be a factor as well. If Boston is where you want to be next year, then Harvard may be the better choice.
Overall, I think Harvard clearly has a wonderful program (after all, it's my top choice). If Harvard is your dream school or if there are particular faculty there that you are inspired by, then perhaps Harvard is worth the money. If you plan on going into academia, then Harvard would be a wise choice as well. However, it seems as though there is not much of a difference between top schools in terms of where your degree will get you and the opportunies that become available. I think that UWash (and many others) are widely recognized in the public health field as being very impressive schools. I have even seen a comment on this board that said BU, in some respects, was just as good as Harvard (according to a Harvard professor)...especially if you were interested in a field such as pharma policy.
Anyway, good luck with your decisions! I think talking with current students and faculty from your potential schools is the best way to make a decision. If you explain your dilemma, I bet they would be willing to offer some (hopefully) honest advice.