it gets easier as the kids get older. it also helps to have interesting hobbies yourself that you can involve your kids in.

so instead of asking: how am i going to entertain this bunch on rainy weekends, ask: what hobby might i like to pick up that i can get my kids interested in.

i have been struggling with that too. i am considering things like learning an instrument, programming, playing board-games.

i found a simplified version of DnD, made it even easier and combined it with using lego to build the environment (including treasure boxes)

and when it's not raining there are plenty of outdoor activities to choose from.