This topic hasn't been discussed in a while that I recall, but there have been many discussions on FAKs over the years.
What goes in the kit has alot of "depends" to it. It depends on what your training is, it depends on how big your group is, it depends on your own "normal" needs, it depends on how far out and away from help you will be... Far and away the best thing you can have in your kit is training. Wilderness-specific training is by far the most useful because it requires you to think outside of the 911 box. Most first aid training is pretty basic assuming that you will be close to a phone and 911 will be able to respond quickly. Wilderness-specific training will help you know what you can manage in the field and what should spell the end of a trip (an attack of severe diarrhea/vomiting and/or dehydration is likely an "end your trip" event in many cases, a cut or knock on the noggin might not be). Once you get the training you won't need to ask the question.