I tend to believe that Columbia offers the most challenging academic program of any school in the nation. I have friends at top schools all over the country, and no one's workload compares to mine. The reason for this starts with the Core. Every undergraduate is required to take a number of classes specializing in Western civilization, aimed at making students well-rounded intellectuals. The classes include Masterpieces of Western Literature, Contemporary Western Civilization, Masterpieces of Western Music, Masterpieces of Western Art, University Writing, Frontiers of Science, and Global Core (classes outside of the Western realm). These classes are capped at roughly 20 students, and are each a healthy amount of work. Most students who come to Columbia want to do the Core, and it is extremely rewarding. That being said, if you have no interest in doing it, you will hate your life, and I advise you to look at Brown or some other school that has no requirements.
Most students spend their first two years completing the Core, and then they choose a major. The most popular departments here are Economics, Political Science, History, and Psychology. Often it seems like everyone is majoring in Econ! I started off as a Political Science major, but after taking a class with Eric Foner, I switched to History. The History department here is tremendous, boasting such luminaries as Foner, Barbara Fields, Ken Jackson, Alan Brinkley, Rashid Khalidi, and Richard Billows. American history is the most popular specialization, and the 19th and 20th century programs are the best.
Since most classes here are small, most of the professors will learn their students' names (especially in Core classes). Most of the professors are approachable, and many are willing to help you with whatever you need. They all live in the city, so it is never hard to meet up with them if you need something.
Because this school is, at its core, a liberal arts college, classes are not geared necessarily towards finding a job. That being said, it is not hard to get a job after college. Most people I know plan on going into the financial industry, and major investment banks and firms are always on campus recruiting. Surprisingly, you don't have to be an Econ major to work for them, but many people here are. Past that, a number of students are pre-law (like myself) and pre-med, and virtually everyone gets into top ranked programs across the country upon graduation.