I would like a non-smoking room.
'Non fumatori' — stress 'fu-ma-TO-ri'. 'Non' remains unstressed, acting as a prefix here.
Specify this when booking, especially in older Italian hotels that may still have designated smoking rooms or where smoke from adjacent rooms can be an issue.
'Non fumatori' (non-smokers) is both a noun and an adjective here. 'Camera per non fumatori' is the full phrase. Since Italy's indoor smoking ban (2005), most hotel rooms are non-smoking by default, but it is wise to confirm.
Fumano in camera nell'hotel?
Do people smoke in the rooms in the hotel?
More direct check of whether smoking is actually occurring
La camera ha odore di fumo?
Does the room smell of smoke?
Asks directly about any residual smell
Avete una politica no fumo in tutto l'hotel?
Do you have a no-smoking policy throughout the hotel?
Asks about the overall hotel policy
Italy enacted its indoor smoking ban in 2005 (Legge Sirchia). Virtually all hotel rooms are now legally non-smoking. However, older hotels may have rooms where previous smoking has left a lingering smell. If this is a concern, ask directly: 'La camera ha odore di fumo?'