Would be fun kid hideout space! Awesome dog kennel under the stairs design idea. If you want an indoor dog house, utilizing the space under the stairs for a cozy, attractive and practical space for dogs is a good idea! I love this design.
Here's an idea for my future house & my dog! Mudroom dog bath: modify to be a full sized shower, but keep the bottom wall raised. Keep washer/dryer as is and my modified "lockers" with dog kennels underneath opposite.