Well before I say anything realize I am nothing more than an anonymous internet poster as is anyone else posting on this board or others. This means I know nothing about you, your situation, or what is best for you. I have gone through law school so I might have a shred of insight, but even licensed lawyers rarely agree on anything so take my advice with a grain of salt.
With that said I will give my anonymous internet poster opinion. LSAT SCORE:
First most people are disappointed with their LSAT score a 165 is in the top 85-90% of test takers I believe. Therefore, there is only a 10-15% chance you will be in the top 10-15% of test takers and individuals that take the LSAT are not dummies they are college graduates who performed well in undergrad, and are motivated enough to take the LSAT, and had enough faith in their performance not to cancel their score.
It sounds like you worked really hard if you did 20 practice tests a 158 may be the best you can do. Many people don't perform as well under "REAL" test conditions some do better it is individual to each person.
The LSAT is the first time many potential law students don't do as well as they expect and that is how the law school road usually goes. First day of class at any ABA school everyone is quite certain they will be in the top 10% of class. If 100% of students think they will be in the top 10% of the class it doesn't make a math major to figure out 90% are going to be disappointed and speak to any lawyer they will convey they did not do well as they expected or at least 90% of lawyers.
Furthermore, most students don't get into T14 schools with 200 ABA schools out there it stands to reason only about 10% of lawyers went to T14 schools. WHAT DO NEXT WITH CURRENT LSAT SCORE:
If you were planning on applying this cycle I would encourage you to apply with your current numbers. If you put off law school life is probably going to get in the way a job, romantic relationship, family, child, or simply believing you will do better the next time will delay the process. I have known a few people that have perpetually studied for the LSAT for years.
With that said I believe most schools will consider new LSAT scores while your application is pending. So you could schedule yourself for the October and February LSAT while your application is pending on your top schools. I am almost certain schools do not average your LSAT and if you improve dramatically they may accept your or you can re-apply next year if you actually have a top score. If you get a similar score then that is probably the best you can do. Under that scenario you are in an everything to gain nothing to lose option. BIGLAW
If that really is your goal then I suppose you will need to go to a T14 school, but even at the schools you mentioned many attorneys are not hired in Big-Law and even ones that do cannot stand it and leave. I have several friends that went to Harvard and burned out on Big-Law in two years. It is often not as glamorous as people think, but each person's goals are different. If you haven't worked or been exposed to a BigLaw firm I would recommend seeing it first hand before making a life-altering choice based upon it.
Furthermore, only about 1% of lawyers work in Big-Law and even from those schools it will be highly competitive. Not trying to say it can't happen, but as my explanation regarding LSAT and Class rank goes to show it is a HIGHLY COMPETITIVE industry and it rarely goes how anyone expects.LOCATION/SCHOLARSHIP/PERSONAL FEELINGS REGARDING THE SCHOOL:
It looks your looking at East Coast schools you I am presuming you live in or around the East Coast. Something very few 0L's actually take into consideration is the location of their school. Remember law school is a 3 year commitment and it is a long 3 years. During that time you will be a human being and you will miss friends, family, and so forth during that time. The further away you are from a support structure the harder school will be. Some people can handle being away from everything others can't that is only a question you can answer.
Scholarship money getting out of law school debt free is something to always consider from any ABA school. Not only are you going to have a 100k or so in debt, but remember this is accruing interest at a 8.5% clip per year and even if you get the Big-Law salary which odds are you will not that is going to be a lot of money. The interest alone comes out to 10,000 or so annually and if you don't get that Big-Law job it is going to be extremely difficult to get rid of that.
However, if scholarship route is how you go be VERY WARY of conditions i.e. 3.0 to maintain teh scholarship. As mentioned all law students think a 3.0 is a joke, but then law school happens and it turns only 35% of students can get a 3.0 and 100% of students think they will be in the top 35% again 65% are wrong. This NY times article does a better job explaining it than I can. http://www.nytimes.com/2011/05/01/business/law-school-grants.html?pagewanted=all
Also take your personal feelings about the school into account. I have been to numerous law schools as a OL and doing mock trial competitions and each has an individual feel to it. There were a few schools I really did not like and others I did. What I liked you may have hated and vice versa. So visit the schools, talk to professors, admins, students, and see if it fits your style. Remember it is a 3 year commitment and if you can't stand a place for a day it will be a long three years.REALITY OF LEGAL EDUCATION:
Although U.S. News a for-profit, unregulated, magazine has decided to "RANK" schools better than the other the fact is the education at any ABA school is nearly identical. First year you will take Torts, Contracts, Civil Procedure, Property, LRW, Criminal Law, Criminal Procedure, Con Law, or some variation on that. Then you should take Evidence, Corporations, Wills & Trusts, and some other substantive classes.
What you learn in these classes will be identical anywhere. From Harvard to 200th ranked school consideration in a contract does not change, hearsay rules are the same, and so forth. Law school does not have necessary equipment like a Med-School or Engineering school all your doing is reading out of a book and having a professor tell you the law. The Supreme Court cases are the same whether you read them in the Harvard Library or read them as an online-law student in your apartment. You will read Pennoyer v. Neff, Palsgraff, Hadley v. Baxendale, all those cases and the words are the same so one school really can't give you a "better education" than the next.
There are better professors, connections, and more qualified students at Harvard obviously, but the substance of what you learn is the same. CONCLUSION
A 158 is not a terrible score you will have the option to attend many ABA schools and likely obtain scholarship money. If BigLaw is your goal then I would apply as planned then reschedule for the October and February LSAT (if your ideal schools don't penalize you for that then your in an everything to gain nothing to lose situation. If a 158 comes back or worse then schools like Seton Hall will likely accept you and you can go on to have a fine legal career although probably not Big-Law.
-Also remember I am an anonymous internet poster who could be strung out on crack and full of it or have good intentions and be 100% wrong in everything I have said. This applies to any other anonymous internet post you see out there and I cannot emphasize enough the importance of taking everything you read out there with a major grain of salt. Michael Scott does a good job explaining why http://www.youtube.com/watch?v=kFBDn5PiL00
a little humor for you.
Good Luck and hopefully you get a 180 on the retake!