Yes, using a VPN on hotel Wi-Fi is completely legal in most countries, including the
United States,
Canada, most European nations, and many other regions worldwide. VPNs are legitimate privacy tools used by millions of business travelers and tourists daily.
That said, a small number of countries with strict internet censorship laws have restrictions on VPN usage, including China,
Russia,
UAE, and a few others. If you're traveling to these locations, it's worth researching the specific current regulations.