Oxy offers a good spectrum of the class room dynamics. I've taken more than my share of smaller english courses (some classes as small as three other students, though the average is about 12-16) and larger lecture courses (sciences generally fall under this, I took psych and chemistry) of 50 or more students and in all of this I felt that the professor knew me as an individual (all of my professors have known me by name and have been friendly towards me outside of the classroom also) and for every course professors make themselves readily available for one on one help, whether in their open office hours, or by appointment.
I'd say that the classes here in general are taught in engaging fashions. I have a friend who I recommended to take an English course with a particular professor. The friend resisted for a while on the basis that he is a "math guy" who "doesn't get english or literature in a deep way" but a week into the course he found a passion for the work because of the professor and got straight A's throughout the course and was always excited by the professor's lectures to readily share the material with me over dinner.
Every department has the basic run of courses, the 101's and then 200's that are upper level division courses, but then professors also teach courses regarding their particular focus so that you can really study something unique in a deep way with a professor you may have an affinity for. It's this personality manifest in all the courses you can take that really makes the curriculum here a fulfilling enterprise.
The requirements at Occidental force you to take a full quiver of courses, and probably something outside of your comfort zone (I had to take a math course for example even though I hate the stuff) but you will find the multiplicity of discipline exposure will affect you in some way positively and enhance your thinking and application of various concepts to a given problem. For example, thanks to the curriculum, I can include some basic science concepts into my work, and on a practical level: that math class gave me a good enough handle on basic statistics and probabilities that my poker game has improved immensely.
Students are competitive to the extent of demanding excellence from themselves, but thankfully, there's none of that annoying grade comparison to see who got the highest score in classes when papers or tests are handed back. Everyone here I know is driven to do the best they can do, not for the person next to them, but for themselves.