(This advice is not for the true entrepreneur or those exceptional change agents who come along infrequently in our lifetime. These rules apply to the rest of us, the competent, hard-working individuals who will never streak across the sky like a meteor shower. If you don't know if you fit in that first category, then there's a good chance you don't. These rules are for the rest of us).
Number one: never leave a well regarded operation for a less well regarded institution because the weather is better; you're madly in love and can't live without her; or you think you're not appreciated where you are. You can only leave a quality operation once, and climbing out of a lesser quality organization is going to be much more difficult than you think.
Number two: never assume that you alone are capable of changing an organization. There are so many different components which make an organization the way it is perceived, your hubris alone won't fix things.
I realize this sounds like an argument for safety. It is. There are too many complicated reasons why a place is well regarded and others are not. Moving back up the ladder may sound like an easy move when you're 25, but when you're 40, it may look like climbing Everest.