Correct way to say 'everywhere in the hotel'

A common way of saying this is:

Wi-Fi is available throughout the hotel.

It can be expressed in different ways...

• "wifi available anywhere on the premises."
• "wifi available in all areas."
• "wifi signal available in every room."
• "wifi in all accommodations and public areas."

Your sentences are grammatical but not idiomatic.

if you're looking for something short, hotel-wide wifi.

When I run into similar "how do I say this better" type questions, I often either change the wording or the order. In this case, I'd change the order: "the whole hotel has Wi-Fi."