Monday to Friday the older two are obviously in school during the day. The youngest is in nursery three half days a week (until 2pm). They also have activities after school, and some at the weekend (Saturday mornings mostly), so during the week there's not a lot of time that needs to be filled.
On 'free' days, so out of term time and a day and a half of any given weekend, we'll often do at least one thing with them outside of the house, whether that's going to somewhere like the zoo or a range of other museums and similar that we can go to locally, or a more defined day out to somewhere a bit further away. But we'll at least go for a work or get out of the house in some guise. For longer school holidays we usually go on some sort of holiday or trip ourselves.
So there aren't a massive number of days when there's a significant amount of dead time. But for when there is, never underestimate the ability of kids to occupy themselves. They really are very good at it when they don't have screens as an automatic fallback. Just off the top of my head from the past week, they play with Lego, we have a little music player with different discs (nursery rhymes and other sound effects) that our youngest loves, we have a piano and drums that they will often sit down and play (eldest is the piano player and middle child is the drum player, but they are learning each other's instrument too so often switch), they race around the house on indoor trikes and scooters, we have a marble run, play kitchen, train sets, they play football in the house, they build forts using both the play sofa that we have and other furniture, they used walkie talkies to speak to each other whilst at opposite ends of the house. As well as books they really enjoy board games, and can seriously come up with an absolutely limitless number of games themselves. They made 'human sandwiches' the other day using the play sofa. Yesterday when I was with the youngest whilst the others were swimming, we spent a solid half hour just emptying the jar of marbles, putting them on a little slide that we made from other toys, and then putting them back in the jar. All of which was apparently hilarious.
That is off the top of my head and just scratches the surface, and I haven't even mentioned when they go outside to play games. For the most part, it's great as a parent to engage with your kids (and you need to in order to give them that confidence to go and play and explore themselves), but you shouldn't need to constantly come up with things to occupy them. They're plenty good at doing that themselves. Even the two year old will play by himself for pretty extended periods of time. Obviously I can't just leave him to it, but giving him enough proper attention pays off later on. I had three hours with him yesterday while my wife was with the others, and I probably read for a solid hour of that in the room that he was playing in. It's obviously not the most relaxing and interruption free reading time, but it's not three solid hours of playing with toddler toys either.
