Instead of Playpen

[torontokids]

You could use gates to section off certain areas. I have a baby play area that has been divided using my toy shelves. It's really just a visual barrier as I have the one end open but it works.

[Kellybelly83]

What about one of those stationary exersaucers/jumpers? Most non walkers love those (although it can be quite hit or miss ha ha) because they can stand up and interact with the other kids etc. My kids loved those, and the newer ones are great because they can spin around and play with all the different toys that are attached to it. You can get them for a good deal used, and even on sale at walmart etc. I know I will have at least one when I open my dayhome!