Stony Brook -- 15,600 promised plus summer support all but guaranteed for American students (?) averages about $3,000. You pay a nominal fee for health insurance (low for families as well) and TA every semester. You do have to become an instate resident (not a guaranteed process) or make up the difference between in-state and out of state. For a full time student, that would be about $7500 a year if you do not qualify. All students on the job market currently started in Fall 2008, so there is evidence that you can finish in 4 years.
Syracuse -- $16,500 plus $3,700 in two summers health insurance included unknown about family plan. Competitive grants in subsequent summers. Sounds like a minimum 5 year commitment with TA duties every semester.
Boston University -- $19,600 for nine months, health insurance included for student, not for dependents which is pricey. Nothing guaranteed for departmental summer support but there are opportunities for research grants and teaching summer classes. Those with an MA (or MPP) have reduced coursework so they could take as little as 3-3.5 years though that varies by person.
This is in addition to what others have posted on the board.