I have just come back from a family portrait session. These can be great fun especially as I tend to shot at people's home. This makes people feel far more relaxed and if they feel like a break they just go and put the kettle on. It is also great for distracting the little ones as you have their favourite toy at hand to wave above the camera to get their attention :)
I use a combination of Bowens 500W/s mono blocks and reflectors along with a white backcloth for the High Key photography, which has remained popular for the several years now.
Camera wise, I use Canon EOS-1Ds Mark II and a 24-70mm F2.8 L lens with a setting of 1/200 f14 ISO 100. THe 24-70mm lens is great for groups like this as the focal length allows you to get both group and individual shots. F14 aperture allows lots of depth of field, which is what I try and achieve on portraits like this. Typically for this type of effect, I like to use a 3 mono block system with the key light as a shoot through umbrella and 2 lights on the background itself which are set a couple of stops brighter than the key light. This setup is easy to transport to most locations that I want to shoot. As most of these are taken indoors there is no need for a power pack but I always take an extension cable with me just in case of a power socket shortage.