They play all by themselves - and they have fun.  I love to put my ear to the door, and listen to their imaginations and conversations.  Harper is pretty convincing, and is working on her leadership skills (it's not 'bossy' - it's 'leadership').  Bennett is pretty patient, and quite good at getting his way - by convincing others it was their (her) idea.

They called for "MOM!" about 45 minutes in, and begged me to take a picture.  They even had the caption ready:               

JUST HANGIN' OUT