That sounds right. Let's look at something like a leaderless unit of Stygian, or more close to my heart, the Desert Wolf Warriors of the Wolf Clan Dwarves. Go Dwarves!! I'm using these because they've got 4 inch movement, and could really get away with breaking the rules with a 6 inch run. With speed like that, it would be easy to move further and then illegally charge a further unit. I say go with the rules as written, and charge the nearest unit.
If you want to reposition and go on wait, that's one thing, but cherry picking the unit you want to charge is not only against the rules, but doesn't reflect the realism of trained soldiers on a battlefield, even in a fantasy setting full of magic. Soldiers have to worry about the nearest threat to them and their comrades in arms. Remember, they are in a fight, not in a chair pushing painted models on a table, so put yourself in their boots, so to speak, and think on it that way.
Of course, you can make an LD test for a model to charge a further unit, but that's very risky. Most grunts only have two actions, but if it means charging a model 3 inches away versus 1 or 2, and you feel it's nescessary, then go for it.