In the end you have to go with your gut.
I think the key to writing a great story, is when you're writing it, the journey along the way that is, that you are so excited you can't wait until the last key is hit on your laptop. Of course there will be revisions, but when you believe and feel it, you'll know when it's right.
My father (he passed away before his time 11 yrs ago) was a master storyteller. He would always tell my sis and I bedtime stories and we'd be all laughing and giggling ourselves to sleep. Using words, he brought some fun characters to life. I'd like to be as good as he was, but on paper, and in a different genre. He would have made the greatest children's books. He was actually working on one before his death.