We've noticed that children like to bring toys and books from room to another, from one floor to another. This can make clean up time take longer than it should. Instead of fighting it, work with it.
I keep baskets in certain rooms on different floors of the house. Something like these Color Block Bins from PB Teen is the right shape and size. There is one in the master bedroom that is currently overflowing with books pulled off the childrens' main bookshelf. There is one in the living room for favorite toys of the moment. There is even one in a lower kitchen cabinet for cooking and baking-related fun. I do have a rule, however, that certain toys don't migrate to different parts of the house. Legos are an example - they stay in the big Lego bin when not in play. You can buy the Color Block Bins here.