"Suggestion" as in "hypnotic suggestion". The spell description does provide control to a considerable degree. The target "will follow" the suggestion unless it is completely alien to his nature (or in later editions, if it is self-destructive). Also, it applies to a single act, not a single thought or idea. You can make someone admit you to the ball, but he won't believe you're a VIP on account of a Suggesion spell, because that is not a act, but an attitude or belief.
As for Charm Kind, that merely makes the caster seem to be a good friend, so it depends on the type of information sought. A typical military type is not going to give up classified information just because he likes you. On the other hand, if you are trying to get the Duchess's maid to gossip about the lady's jewelry, she is likely to comply. In some cases, you might find the target willing to give up the information... if properly paid. Charm Kind, however, has a 100' range and if the enemy leader thinks his force is attacking a friend, he's likely to at least be ready to negotiate. It seems a likelier candidate for battlefield use, at least if the PCs haven't been unduly aggressive (in which case, making the enemy leader think you are a friend is likely to just make him feel betrayed).