Can bankruptcy be a good thing?

I have a mortgage and two car loans (for my car and my wife's car) as my major bills. I am working steadily making about 45K a year. I have student loans but they are in deferment while I finish my PhD. By the time I get the PhD I will probably owe almost 90K in student loans. I'm thinking about bankruptcy as a possible way to get rid of the mortgage and car loans and start attacking the student loans.