Packing for kids: how many toys to bring?
This is a constant source of decision making stress, and packing weight for us. Some kids don't play with toys, for them, a few small, familiar things and a tablet and / or portable game system are all they need. Those are not our kids. Both of our girls play with Barbies, mini princesses, Shopkins, Playmobil, Legos, and any other little toy one could imagine, for hours on end. For them, it's highly likely that anything we pack will actually get played with. Instead of making packing easier, this actually makes it harder, because they would prefer if we brought everything. For this 6 months in Europe, I packed only the toys they received for Christmas, which was only 5 days before we left, so everything they have is new and exciting. Once we are a few months in, picking up a few (very) small new toys will make all of their toys seem new again, and can help eliminate the "Mom, everything is boring!" exclamations all parents are thrilled to hear.
As far as packing space goes, the kids toys take up the majority of the space in our suitcases, but not the majority of the weight. I would like to point out that we are not on vacation, we are living abroad, so we pack for it. For a vacation with kids, I recommend giving each child a backpack sized correctly for their age and strength, and let them choose what to pack in it, making sure to explain that the only toys they will have while traveling are the ones in their backpacks. At one time that was exactly what we did, and some day we will be there again, but for now we are packing heavier.