I believe Bobol makes a good point get your LSAT score and see what your options are. You can putz around getting A's in frisbee golf for years and end up wiht a 3.8, but with a 154 LSAT or something NYU is not accepting you.
In regards to your specific situation I don't think schools look down on GPA padding I inadvertently did it myself playing sports in college and my numerous A's in the sports I played got me a lot of scholarship money to law school, but to spend a year of life your doing that without even knowing your LSAT score is probably not a good idea. If you come away with a 170 then it might be a decent plan, but as Bobol says your putting the cart before the horse it will truly be a waste if you spend a whole year in college getting A"s in joke classes and come away with a 154 LSAT and end up in the schools you would have ended up in anyways.
Also you do not have to go to NYU to succeed as a lawyer. I myself did not go to Harvard or a T14 school, but I passed the bar and work as a lawyer now it happens.
A final thing I noticed is that your dream is to live and work in NYC. Now I might be reading into this, but have you ever lived in NYC? I have personally and there was a lot of great things about it, but a lot I did not like and if you have not lived there I think you would be much better served spending a year living in NYC getting the lay of the land and seeing if you can handle it before making a 3 year commitment in the most expensive city in the world.