The fact is, most people take nothing, and do just fine. It isnt at all common that anyone has problems. Being on top of your game attention wise, having a plan if a bear comes close, like getting your people slowly into a group, with the people with pepper and weapons up front, and being cool headed will deal with all but the very most remotely bizarre occurance.
I'd also suggest to be sure nobody is going to FREAK OUT and scream. If they do, have somebody understand that they should grab them and make them stop. It doesnt have to be polite, it should be very fast.
Women during their period are generally thought to be a bear attractant. Its best if they arent running around in back country at that time. The regular stuff with board walk trails and lots of people, I wouldnt worry much about it.
I've lived around grizzly country for more than 25 years. Yes, theres occasionally problems, but hardly on the scale that many seem to feel. It sounds trite, but its true. Its more dangerous to drive to Yellowstone than to get out and enjoy it.