Highly dependent on location and your interests as far as research go.
Attendings at most large academic PICU's are going to have 16-18 weeks of service if they are clinician educators. Those doing bench research are more likely to in the 6-8 week range of clinical service time - but with the expectation of doing research that will grow a lab and earn extramural funding.
Non-service time is not your own, and you'll need to be academically productive, involved in department and hospital committees and teaching students and trainees. Not all academic departments are the same, and the expectations for academic productivity will be very different. Some places, you better be publishing 2-3 (or more) papers a year. In other locations...one publication every 2-3 years will be sufficient.
At the moment, everyone wants people with cardiac experience - which for new fellows means either dual boarded or at least a 4th year Cardiac ICU program. Even big programs seem to be frequently understaffed, and CICU attendings seem to work harder than those of us only in the PICU. Despite that, my perception is that the push to publish is equal or even greater for those in the CICU.
Private practice PICU's will be more service time, but without the responsibility to publish. Usually are smaller, but service weeks may be 7 days on, 24 hours/day. Usually the salary is better. Private practice is harder to find locations that are of sufficient volume and acuity for newly graduated fellows as there still is a significant learning curve in the first 2-4 years after fellowship before you're really a true bada** intensivist.
Call volume also very different. In most situations it's reasonable to expect between 35 and 42 nights of coverage per year - maybe a little less. Most places are going to 24 hour in-house attending coverage. Coverage models vary between night float and more traditional rotating calls. I work 5 weeks of nights a year, and I find it more satisfying for my home life than doing 3-4 nights a month. You have to remember that in most academic places you'll probably work through the following evening after a call night, so you'll go home at 5pm rather than 11am like the residents or fellows.
ICU attendings frequently take part in the sedation service for procedural and imaging sedation. May or may not be part of your required duties, so it may be moonlighting or not.