You all make some pretty convincing arguments regarding whether or not we should, or even can make it to Mars over the Moon.
That being said, I think the Moon has just won out given that Space X will be sending two paying customers on a trip to orbit it. Let's look at it this way. It may cost a billion $$$ per a customer right now, but those costs would only decrease as time goes on and the technology improves. Therefore, such a vacation would become available to lower paying customers. On top of that, these two guys going up next year won't even get to land on the Moon. I don't know about you guys, but if I was going to the Moon for a vacation, then I would want to actually step foot on it. So, I think it's safe to say that we will eventually see some kind of facility built on the Moon for people to land and vacation on.
To end, I think it's a little funny how none of us posting had given much thought about the business motivations for selecting either the Moon or Mars.