Have you ever noticed that it's nearly impossible to win an argument? That doesn't mean you can't persuade someone to move from their original view to your view. It's just that it probably won't happen as a result of an argument. The reason is that, while in the "argument" stage, the person will probably be too busy "defending their turf" to be able to step back and understand why your view is the more reasonable. Funny how that works, isn't it? :-)
The key is to first, end the argument. How? By agreeing. Now don't get me wrong. You don't have to "sell out" to do this. However, there's always something within what they say where you can find agreement, even if it's just how they feel, or their right to have those feelings.
Example: You arrive at the hotel much earlier than the usual check-in time. The person at the desk tells you that it's against company policy for guests to check in before the regular time of 3:00. You could logically argue that, as long as a room has been cleaned, it shouldn't be any big deal. But, that would cause the employee to admit he's wrong. Most people have an ego that doesn't enjoy that feeling.
Instead, agree with him: "Yes, I understand what you mean. It's hotel policy and that needs to be respected. I can appreciate that."
You didn't argue with him. You agreed with him. Personally, I don't imagine he'll argue with that. What's he going to say? "No, you're wrong. I'm totally wrong about what I just told you." :-) No, he's going to feel good about you, because you agreed with him. He's going to relax because he knows you are not being confrontational.
Now, you can help him to "live in the solution" with your suggestion: "You know, I'm wondering. Just if it's not too much trouble, could you check to see if perhaps one of the rooms has already been cleaned. I think that's probably the reason for the rule, which would make a lot of sense." Then, I would add what I call the "Eight Key Words", which are, "If you can't do it, I'll definitely understand."
More than likely, you'll get to check in early...and get one of the really good rooms. I can tell you that from personal experience, and the many letters I receive from people who do the same thing.
Remember, first agree. Then (and *only* then) persuade.