All of these are good suggestions. But I would lean toward a couple of factors to make the decision. First, what is convenient and comfortable--if there is something nearby, then go take a look at it and maybe get excited to dig a little deeper or journey farther afield. Second, is there someplace that piques the interest or imagination. People tend to shy away from suggesting Gettysburg as a first visit because of its massiveness and complexity, but that grand scope and all of the stories can make that first visit rewarding and compel the visitor to keep returning and hunger for more. The important thing is to visit somewhere and start that itch so it needs to be scratched.