One thing nobody told me (and it won't make much sense until you are a resident) is how imperfect the experience of residency is. As a medical student, you're basing your choice of a place to work on "feel-good" feelings -- which may involve factors such as reputation, busy-ness or craziness or quiet calmness depending on what floats your boat, relatively good hours, etc. Guess what, you can get all of those things (on paper, or in your own notes) and still feel happy some of the time, and crappy some of the time. Residency is full of ups and downs, same as medical school. Residency is also a job with all of those ups and downs -- dealing with annoying, immature people day in and day out. And it's not like back-to-school: you're not going to jump for joy about returning to work after your vacations are over.
That being said, you can still be very happy with your job and your residency program as a resident. It's just not because your hospital doesn't have annoying unit secretaries and passive-aggressive nurses (because your hospital will have them). It's because of "other factors", and I wish I could tell you what those intangibles are. I don't know.
Finally, one very tangible thing that surprised me a little was how much difference the hospital's overall financial status (losing money, or earning money?) makes in helping you out. Yes, you can be happy at a money-losing hospital, but there are a lot of things that a hospital that is actually earning money can offer. This includes better ancillary services (you mean you don't have to draw your own cardiac enzymes?), more professional nursing staff, a book budget for each resident (my internship had a "book budget" of $500 to share among ALL THIRTY residents, and my residency gives EACH resident $500 for books), and better employee benefits such as health insurance. These perks don't make up for working in a department with crappy attitudes and a poor work environment, but they can make a good department better.
