You on the other hand, having done the research and preparation, are quite confident of what you'll find in Disney World and have no second thoughts about going there. You drive straight there, have a ball at Disney, and come home refreshed and pleased with your vacation. Everything happened just as you planned.
Here is the question: Did all your prior planning, which lead to a confident expectation concerning what would happen on the vacation, somehow constrain your freedom of action? Is there some conflict between your knowledge of what was going to happen and your ability to "change your mind." Are you a hopeless slave to your knowledge and am I a true free spirit?
Richard Dawkins seems to think so, at least given what he writes in The God Delusion. While discussing arguments for God's existence, he says this in passing:
Incidentally, it has not escaped the notice of logicians that omniscience and omnipotence are mutually incompatible. If God is omniscient, he must already know how he is going to intervene to change the course of history using his omnipotence. But that means he can't change his mind about his intervention, which means he is not omnipotent.
I hope we can see from the vacation example that "changing your mind" isn't really an expression of power and freedom; it's an expression of weakness and ignorance. We change our minds when we realize our actions are counter-productive; and that happens when some mistaken view of the world we hold gets corrected. Since God is omniscient, He's never in that position. He's never mistaken about the way things are so His decisions are always optimal. That makes Him more powerful, not less, because He never wastes his energy on useless or counterproductive endeavors. Sure, God always knows what He's going to do, but it's not possible for Him ever to have a reason to do anything other than what He will do.
The deeper import of the apparent "conflict" between omniscience and omnipotence is its basis in the modern understanding of freedom. Freedom, for the modern mind, is found in the spontaneous act of the will uninformed by the intellect. This is why Dawkins sees "changing your mind" as just another arbitrary choice, like deciding you like chocolate rather than vanilla ice cream. "Know the truth and it shall make you free" is the foundational principle of classical philosophy established by Plato, because Plato saw the rational soul of man as an intrinsic part of nature. It is man's nature to know the universe, and through that knowledge he rises above his beastly nature and expresses the freedom unique to him. But the Enlightenment brought in the idea that the universe is fully governed by non-rational laws (e.g. the laws of science); the rational principle essential to man's nature is either placed outside nature (Kant) or simply denied. In either case, reason only applies to the universe known by science, and reason only reveals ever new laws that govern man's behavior. The more man knows, the more he realizes his actions are dictated by unconscious urges, psychological conditioning, genes, etc., etc. Freedom, it turns out, is only an illusion that persists as long as we are ignorant of the forces controlling us. It's not knowledge, but ignorance, that makes us free, or at least grants us the illusion that we are free. This is why Dawkins grants such significance to the act of "changing your mind": It's the paradigmatic act of modern freedom.
This modern and paltry understanding of freedom shouldn't be laid at the feet of the God of classical philosophy. His freedom is much more profound.