I've set up our playroom to be as organized and open as possible. The kids love to run amok and need plenty of space to do so. Since our downstairs is only around 750 sq feet I decided to devote one of the rooms for their use. We are planning on homeschooling our kids but won't officially start for a couple of years. We may still be in this house at that point in which case this would become their work room as well. For now though, it serves its purpose well.
This is the main entry into our playroom, being at the front of the house. The floor is covered with square foam mats that link together like puzzle pieces. Our entire downstairs is hardwood so they're great for extra cushioning (especially when kids are learning to walk.)
This is our current storage wall. So far, it's just the one bookcase and desk which serves as a changing table and place for child care supplies. I think in the next few months we may get a second bookcase to expand our storage and staging areas. The low exposed shelves display several activities and toys for the kids to use when they want. The top of the bookcase has doors which allows me to store the rest of their toys/activities conveniently out of sight. When I notice them not playing with something for a few days I switch it out with something new. This way there isn't an overwhelming number of toys for them to be distracted by.
Once you open up the doors you can see what I mean. Organizing like this also helps me stay on top of what they're playing with; things that are broken or they are too old for get thrown out/put away quickly instead of adding to a growing pile of "stuff" in a huge bin.