Here is an idea we did while we had company over a while ago. In this situation, M. & Friend needed some quiet to do their Bible study, so Little Girl & I got to play.
It's not a very clear picture, but what we chose to do is throw a bunch of pillows, rugs, blankets, and boards on the floor and we had our very own "Green Sea" full of alligators and quicksand. (Yes, both in a sea)
We had treasure to keep away from the pirates, and so spent the whole evening jumping from lilly pad to lilly pad, squeeling away from aligators, and running breathless into our "cave" away from any pirates.
Above, Little Girl is trying to resuce Friend from said alligator....but it seemed a little late.
So there you have it....you don't need a bunch of stuff to keep kids happy if you've got a little imgaination and a lot of engery!