Joffre,
from the jersey side, two possibilities:
for lower manhattan: Liberty State Park in Jersey City. exit 14B from the New Jersey Turnpike and follow signs. the lower (southern part of the park overlooks the back of the Statue of Liberty with manhattan/brooklyn in the background). the upper (northern) part of the park has a nice view of the world financial center and lower manhattan.
for midtown (better in my opinion) Weehauken/West New York begining about 1/4 mile north of the Lincoln tunnel, a park runs the length of the river across from midtown, begining across from 23rd street up at least to 59th street. Best pictures are from the south end of this park, directly across from 42nd street. get there in time to scout around. be advised there is heavy traffic in the area due to the evening commute.
drop me an email if you want more info.
Tom