"Farewell!" they cried, "wherever you fare, till your eyries receive you at the journey's end!" That is the polite thing to say among eagles.
"May the wind under your wings bear you where the sun sails and the moon walks," answered Gandalf, who knew the correct reply.
It's one of the many reasons I have such a crush on Gandalf. I would love to be so gracious, so thoughtful, and so learned, that I know the proper formula to wish anyone well according to his own culture and the things that are most important to him. I'll have to take another look at Stuart Little, but as I recall he does this more than once, coming up with just the right thing to say off the cuff. Off the cuff, but taking a moment to think about the person he's addressing and that person's circumstances.
I know, of course, that it's--forgive the expression--the thought that counts; but words are important to me, and I think words that have lived together in the same phrase for so long (as in the Gandalf case) take on a life of their own.
Here's one that made me feel particularly blessed at our wedding:
The Lord bless you and keep you; the Lord make his face to shine upon you and be gracious to you; the Lord lift up his countenance upon you and give you peace.
Or, for the fishermen among us, "Tight lines!"