No way would Darcy have been happy stuck in a playpen once she was mobile. We had a gate across the kitchen (occasionally) and one across the stairs top and bottom. She never tried to touch the oven or get into dangerous stuff. We gave her one cupboard that had her stuff in it and she played in there for ages. The rest of the house we childproofed. It was too open plan to shut one bit off and I reckon I'd get bored in one room for any one period. We did have latches on cupboards just in case.