Well first off realize that most people that spend time knocking things anonymously on the internet are really not worth listening to and realistically anything you read on boards such as this or others coming from anonymous internet posters myself included should be taken with a grain of salt. Michael Scott gives a good explanation of why that is true a little humor for you. http://www.youtube.com/watch?v=kFBDn5PiL00
In regards to the specific situation if you want to be a prosecutor in New York I think CUNY is your best bet. They are one of the few schools that offer in-state tuition and as Jack mentioned the best thing you can do is get out of law school with minimal debt. CUNY is only about 10,000 per year or so and you don't have to worry about scholarship conditions.
There are also other factors to consider when choosing a law school and I have posted these factors in other threads in more detail, but my two cents is these are the factors you should consider (1) Location (2) Cost (3) Personal Feelings about the school (4) The reality of legal education & specialty programs. (5) U.S. News Rankings as a tie breaker these is something to consider, but don't let a for-profit, unregulated magazine, be the basis of a life altering decision.
Another thing I think you should also realize many of the numbers produce from law schools are not very in depth and should not really be considered. Employed what does that really mean furthermore the reality is a reason for a lot of people not obtaining employment is not passing the bar, which many people even from Harvard don't do the first time around. As Jack mentioned Federal Clerkships will be damn near impossible to get, but to be a D.A. in some county somewhere if that is your goal and you pass the bar it can certainly happen.
Here are the reasons why the factors I mentioned above should be considered.
As others have stated and you seem to realize it is extremly important you go to law school in the area you want to live in after graduation. Law school is three years of your professional life and during that time you will likely make many friends, enter into a romantic relationship, get an apartment you like, and more importantly most of the internships etc you obtain will be in the area you attend law school.
This is extremly important and the best thing to do is get out with as little debt as possible. State schools offer that and I know CUNY in New York, Florida International in Miami, Univeristy of North Dakota, University of South Dakota, Wyoming, and a few others are less than 12k per year.
You may also get a huge scholarship from various other schools, but pay attention to the conditions on these often they will require you to obtain a 3.0 at the end of your first year and almost anyone that is offered a scholarship at an ABA school likely could get a 3.0 in college with minimal effort, but that is not the way law school works because of the curve. Generally speaking only 35% of the class can have a 3.0 at the end of first year and believe me 100% of people on the first day of law school are convinced they will be in the top 10% of the class, but as a finance major I imagine you can do the math and see what happens when 100% of people think they will be in the top 10%. If you lose that scholarship then you pay full price for years 2 and 3 which can be a lot I think Brooklyn for example if 40k or so per year so just be wary of any conditions on scholarships you recieve.
3) Personal Feelings about the school
I was accepted to numerous schools and visited them all prior to attending there were some I liked some I didn't and those were my personal feelings. You should visit all these schools and see the facilities, talk to professors, talk to the students, just get a sense of the place and see if it is a fit for you. This is very important because nobody knows what you like better than yourself. So make sure the school is a fit for you personally.
4) Reality of Legal Education & Speciality Programs
Every ABA law school teaches you the same exact thing first year is Torts, Civil Procedure, Property, Contracts, Criminal Law, and Constitutional Law. You will probably get use the Contracts book written by Eptsein a The Con Law Book written by Chemerinsky etc and in Torts you will read the Palsgraff Case, Civil Procedure Pennoyver v. Neff etc and what you learn will be the same.
You want to be in Public Interest and there are some schools that specailze in that, but realistically as a lawyer I still don't necessarily know what specializing in public interest means. They might have clinics etc, but to be a D.A. the best thing to do would be mock trial competitions so I might check out what schools are active in mock trial competitions, because that is some of the best stuff you can do in law school if you want to be a litigator.
5) U.S. News
So many 0L's take these way to seriously and don't realize it is a magazine offering an opinion nothing more. U.S. News also ranks Alberquue New Mexico as the best place to live, but you wouldn't move to New Mexico just because U.S. News says to. There may be numerous reasons for this ranking New Mexico might be a great place, but I am not going to make a life altering decision such as moving there because U.S. News said so. The same logic should apply when choosing a law school consider the rankings, but make it a minimal priority.
Knowing nothing about you other than a few paragraphs on the internet I think CUNY would be the best school, but I know nothing about you and I certainly couldn't say what is best for you and neither can any other anonymous internet poster.
Also you are only in undergrad it sounds like your grades are good, but next is the LSAT before really considering any law schools I would take that test and see what your options are. You can think about different options all day and night, but until you have an LSAT score you don't really know what your options are.