Depends on what you mean by bank. If its the local savings and loan then its not gonna be all that good. If you are talking about a wall street based investment house then it will look very good.
Your target school of northwestern I dont think they really have any students in their fulltime program with less than 2 years experience. You could probably count them on one hand. The same I believe holds true for their PT program...typically students in PT programs are more experienced and are older than even in FT programs. They have reached a level where they need an MBA to continue their career.
There is really no reason to go back right away for 99.99% of the people. If your family owns a business and you are being groomed to take it over OK. But if you are just wanting to move up quickly its not gonna do all that much. If you go part time make sure you work at a place that pays for it.
I know that at FT programs the kids with little experience are at a disadvantage during recruiting because a recruiter would prefer someone with some real life experiences over a fresh out of college kid.