I love love love Cardiac - but what part of the Cardiac process I want to be in is still a big question for me. I absolutely fell in love with ICU during my rotation there (because of the protocols, technology, and teamwork), but I also fell in love with the OR (even though I was not in a Cardiac-centered OR and was more observing than taking on a nursing role, which means I got to see more of the surgeries themselves than the nurse, who was notating and getting supplies, etc). I, like many who have responded previously, loved the NICU, but I also love the adult population (especially the older adult) and love having patients I can talk to.
And it's good advice to ask the nurse you're with during your rotation day why s/he chose to do what s/he does. I ask everyone that. My favorite answer so far was that they had to decide whether they liked their patients talking or not. This can go for whether you're choosing between babies and bigger people or OR and non-OR, so it's pretty good advice to get things narrowed down. lol