Don't you love how NO, DAVID! ends? Everyone tells David, No! At the end, he finally hears, Yes! It's a happy ending, and I happen to love a HAPPY ending.
How about another favorite of mine titled, IF YOU GIVE A MOUSE A COOKIE? The end goes back to what's happened in the beginning. It's a CIRCLE ending. So clever.
In LIBRARY MOUSE, author Daniel Kirk leaves the reader with a MAYBE ending: And maybe this time, his new friend would draw the pictures. Very cool.
Other stories have a QUESTION ending, like: What trouble will he get into next? (I just made that one up, but hey, it's a great ending!)
How will your story end?