Why not get some free gardening catalogues for reading when the weather is too bad to go out in the garden? Plan what to plant next, and so on.
One bit of garden furniture for the kids is a tent, they love the pretense of camping in the wild, while in reality being safe in their garden. This one has
the advantage of being quick to put up, always critical with kids, whose mentality is biased towards the "immediate" and they get bored if anything takes
too long to do. Have a look at the video and see how quick it is to put up this one. I estimate 10 seconds!
Pegging it down afterwards actually takes longer (but not much more).