Choosing a path

After you graduate nursing school and pass your boards, do you normally go for whatever job is available? Or do you have good luck at landing a job in your choice of environment? How do you know which area you would want to work in? I would love to work in a cardiac unit, and I would also love to work with children. Does anyone have suggestions on choosing your path or like I said, does it just go by where you can find a job.
In many areas, it is an employers' market right now. That means there are far more applicants than open positions in those areas seeing a glut of nurses. Whether you hold out for your choice job or accept whatever you are offered is up to you- just understand that you may have to wait quite some time if you hold out for the choice job. Best bet is to research what the job market is like in your area to help you make that decision.