In all honesty, it wasn't that big a deal during the day. They literally would only cough a few times a day, but when an episode hit, whew boy! The youngest was my main concern because she was so little. She would turn blue during an episode. I promptly turned her upside down, every time, and whacked her back like you do when you Heimlich an infant. She slept with us because night times are the worst and I had to be there when she coughed. The other kids, no big deal. They went to school, because they weren't diagnosed (by the time I figured out what they had they'd been in school 3 weeks anyway).
The danger of pertussis is that the mucus is inhaled into the lungs on inspiration after a cough and then pneumonia develops. I made sure that wouldn't happen with the baby by making sure she drained before turning her over again, monitored her carefully and kept my infant stethoscope handy so I'd be able to get her seen at first sign of pneumonia. It's not that hard to hear pneumonia in the lungs, even if you are completely inexperienced.
A healthy lung whispers upon inhalation/exhalation. Pneumonia crackles like crinkling wax paper or plastic.
Here are a couple interesting articles:
http://www.kpbs.org/news/2010/sep/07/whooping-cough-vaccine-working/ -- notice the one doctor who doesn't believe the statistics are accurate because there is "probably more protection from the vaccine then these numbers bear out..." ??
http://www.timesonline.co.uk/tol/news/uk/article684270.ece -- This is an older article from England, but discusses the problem with lack of diagnosis. This isn't only a concern with pertussis, but with all illnesses which have corresponding vaccines. Doctors become reluctant to diagnose, due to the requisite paperwork, effect on statistics or plain lack of experience diagnosing these illnesses.