Ah okay - is there any reason not to book the Mercure relative to the other two since in this case cheaper doesn't seem to mean significantly crappier or the difference between a solid room and a rundown motel situation. It seems to me like between the three I should just book the cheapest one (which is the Mercure) and that for a quick overnight stay they will all provide a basic, clean non-smoking room, airport shuttle, and some form of access to Narita Town for food (either via shuttle or walking).