I am a HUGE fan of letting the girls "just play."
During the play time, I do not engage with them. We call it "sister time" and they must play with each other and without me. My general rule of thumb is "If no one is bleeding or dying, work it out on your own." Before Pandora was verbal enough, I would intervene and help but she is now a mighty force not to be reckoned with. To control tattling (let's get real here, I have TWO girls) my saying is "Are your words helpful or hurtful?" I literally say this over & over until they stop, give up, and go back upstairs. Most times they stomp off with attitude and mumble to their sister "Mom isn't listening."
I AM A-O-K with this being an example of me "not listening." Below is a picture of my pirates going on a treasure hunt.