There's no better place to go for your undergrad career if you want to live in a vibrant and cultured city and, to be blunt, grow up. Students who want to be coddled and have everything handed to them don't like NYU (and probably not NYC). But, if you want to grow as an individual and have the best college experience of your life, come to NYU.
I was originally in CAS and then transferred to Gallatin. I will say that Gallatin has a more tight knit community, with more professors who seem to care about their students, and more interesting classes. With that said, it's department by department in CAS. I found that many of my friends liked the sociology, journalism, environmental studies, social and cultural analysis and chemistry departments. I took a majority of my classes in journalism, french and environmental studies - most of my professors were great, attentive and so well-connected! Go to office hours, talk in class, email them and you will enjoy your classes 100x more! I did have bad experiences with the biology department, so premeds and bio majors beware.
As for gallatin, about 90% of the professors are there because they really care about interdisciplinary studies and helping students shape their concentration. But I have certainly run into a few bad apples. I won't name names, but beware of the guy who is a leader in environmental architecture - he didn't bother to learn our names, gave out unfair and unjustifiable grades, and spent most of his class surfing google and talking at us. My adviser, who was a well-meaning guy, was terrible at responding to emails and, well, proofing my rationale, which resulted in me almost missing very important senior year deadlines. Aside from these two duds, everyone else was great! To avoid these problems, ask around and MAKE RATE YOUR PROFESSOR YOUR BEST FRIEND.
The gallatin program is truly unparalleled, and it personally gave me a leg up in the job search process. In 2013, I secured a job a little less than one month after graduation. I received my first job offer about 2 days after graduation (but turned it down because it wasn't a good fit). I had 4 offers total, and was able to pick which one I wanted. In this economy, it was truly a blessing. Make the best of your time in gallatin or at nyu by doing A LOT of internships, networking, getting a work-study job (also because the city is expensive), being active in clubs and applying to scholars groups. You'll not only set yourself up to get hired, but you'll have the best academic and social experience of your live.
Although I did spend a lot of time at the library, I also had a pretty great social life. My rule of thumb was that I wouldn't study on Friday or Saturday nights unless it was finals or midterms. I made friends doing activities I was passionate about and on my floor freshmen year, and I've kept these friends through my four years at NYU. The nightlife in the village is great - from poetry slams, to great bars, to clubs and comedy clubs. There's something for everyone, as long as you're willing to step out of your shell.