I think it depends on what is concerning you. As taxguy said, PSU may look favorably on it as an admissions factor and future employers probably don't care one way or the other. The best argument against it is probably that you would be missing out on a more diverse educational experience. I think this is less relevant if you are spending a year in DC for work, and much less relevant if you wanted to work in/around PA.
Extracurricular activities really come into play when someone didn't do them. Depending on what they are, though, they could be a nice soft factor. As a side note, it might even be helpful to look at the extracurricular groups in existence and see if there are any you would like to start once you are actually admitted (and find a way to mention it to them). My only word of caution is to make sure that it is actually unique from what is already there.
Your UGPA shouldn't be a problem if you do alright on the LSAT (the 25th to 75th percentiles for UGPA are 3.3 and 3.7, respectively).
As for what you actually wanted to know, let's look at it in ranges:
165+: I would be surprised if you didn't get in.
160-165: You would be a very competitive candidate. Should be fine.
155-160: This is pretty much the school's range. Focus on a stellar personal statement and solid letters of recommendation and kiss it up to God (or whoever). The actual median for the school was 158, so the higher above that, the better your chances of acceptance.
Below 155: Chances of admission drop sharply. If you have your heart set on it, make sure you have a good addendum to explain your numbers (if applicable) and do something interesting as sh*t while you are in DC.