In my uni, there wasn't any designated time limits, my parents were gone within 2 and a half hours. We got there, I had to go to the sports hall to register with the doctors etc (which took ages), get my room key etc etc, then it was over to my accomodation to get me moved in (lived up 4 flights of stairs so it took a while!). Mam helped me unpack bits of my clothes and made my bed and we had lunch in town and then they left.
2nd and 3rd year, I was in self catered accomodation but because I was returning we didn't have to worry about getting me registered. We also had food at mcdonalds before going to the uni. We got me moved in, mam made bed (she chose to, she said at least that way shed know I had a bed to fall into that night), went to Tesco and done me a Big Shop and then they were off again. Probably took around an hour and half, but again not spent all on campus.
I definitely wouldn't have liked the idea of my parents staying close to the uni overnight, could understand if it was 5+ hours drive away, but for a relatively close drive I'd have hated it. Likewise, I'd have hated it if my parents had just dropped me and my stuff off and left me, especially in first year. In the 2nd and 3rd it wasn't so bad but still, them going at the begining of each term wasn't too nice knowing it'd be a while before I'd see them again, so a hurried goodbye wouldn't have done any good either. Take the lead from your dc I think, you know what they're like. I did like the goodbye lunch though - if nothing else it made sure I ate, because I was so busy the rest of the day I wouldn't really have chance - even if it's a mcdonalds it's something!