your student host experience will vary a lot depending on what school it is and who your host is. some will pick you up from the airport, some won't; some will offer you their own bed to sleep in, others will put you on an air mattress on the floor; some will go out to dinner with you, allowing you to pick their brain, others will be busy all night. you can probably get a good feel which of these circumstances will/will not apply to you by talking to your host the day before.
if you are a fussy person i would not recommend staying with a host (you do need to be well rested for the next day after all!), but if you are used to living on the go (ie hostelled at all), i think it is a great way to get at that elusive "gut feeling" that pretty much decides where you eventually will go to school. i stayed with a student host on 4 of my interviews, and i loved it.