In practice you will be fine - just be careful of your own security over WiFi. Re actual legality, someone approached both a leading law firm and the DoJ a week or so ago about whether using a WiFi hotspot without explicit permission is legal under federal law and I believe the answer they got was ambiguous ie under US Federal Law it's not expressly a criminal offence. That's all legal nicety stuff, though, you're fine doing it in a hotel.
