I have yearly books and vacation books. In my one vacation book I have a Niagara Falls trip, 2 Las Vegas trips and 3 WDW trips. I started a 2nd vacation book for my most recent trip in January. I haven't yet but I think I plan to add a page in the reg book saying we went to Disney and go see the vacation book.
For my WDW pages, I usually theme them by park or occasion. I have character meals and parade pages that are mixed parks, but I usually have at least a page for each park highlighting some of the things at each park. When we went in Jan, the holiday decos were still up, so I have pages just for pics of the decos from all areas. I've also added a resort page(s) and special dinners like Hoop de Doo too.
On the last two trips we only took my son, but on the previous trip we took my stepson too and I didn't separate the kids at all. We didn't really take many pics separately, so it never crossed my mind. The vacations are for the whole family, so the scrapbook should be too.
I also write memory stories/trip reports. I take notes at slow points while on trip (we had to wait to be seated at Ohana's for an hour once, great time to update notes). Then when I get home I write the whole story, helped along by my notes and pictures. Having a digital camera is wonderful for that immediate memory jogging, plus everything is in order and dated! After the story is done, I eventually print it and keep it in the vacation book as well, in their own pages with some stickers and embellishments.