My little girl figured out how to get out of her pen in 2 days! So much for her own little "apartment style" space!!
Opi is 6 months old and has full run on the main floor which includes the living room and kitchen, but only while someone is there. We keep her crate in the living room (her big sister has a bed in the living room) so why not her?
We crate her when we sleep until she is older and well trained...and also when we are leaving the house for any length of time. For when we are going to be a little busy to keep an eye her, we have a gate and give her safe space in the kitchen with her water, pee pads, toys and another bed.
I was so bummed when the little 2 lb munchkin decided she was too good for the pen!