I have the exact same pen as Esme's mommy and my little ones stay in all day while we are gone (8:00 - 5:00 with us coming home at lunch time) and have never tried to climb it, however, the cat climbs in and out to eat their food and play with them, and I am hoping she doesn't teach them how to get in and out!

LOL. I couldn't find one at any of the pet stores locally, so I bought it at our local Toys R Us in the baby section for $59.99, it is the exact same pen as Esme's mommy and can be kept in the rectangle shaped or pulled into a hexagon shape that gives a bigger area. I just love it and it is very durable (I have an eight year old that climbs over it all the time).
Here is the link to it at toys r us:
http://www.amazon.com/exec/obidos/tg...=baby&n=540992