I do not think that there are general best practices. But there are different goals that a hotel could have. Some want to make money with the WLAN, some want to provide best guest experience. As a traveler, I of course prefer the second goal.
If your local rights allow this, I would go for the "click through" splash page. The guest has to accept an "acceptable use policy" and is connected to the internet. That is very convenient for the guest.
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