I worked in a neurosurgical icu for the last year and loved it. The only reason I didn't stay is because I want the cardiothoracic icu experience for CRNA school. If I wasn't going on in school then my preference would be neuro. Very interesting! Neuro is not as critical as the other icu's, however (depending on where you go). Often neuro is considered a stepping stone into a more critical atmosphere. If you liked ED and the quick paced atmosphere you might try a trauma unit. Most trauma units do all the bolts and monitoring tight icp's/cpp's with traumatic brain injury protocols. You might get the best of both worlds there. Another intense atmosphere is a cardiothoracic icu in a teaching hospital. You won't likely find sicker patients than in a real busy surgical or thoracic icu. so, it depends on what you want. Being a former ED nurse I bet you'd enjoy trauma. Good luck.