My experience is that the airlines will try to help you, last January I was flying on a NW ticket from Detroit to Phoenix, and then to Tucson on a different ticket on America West. My NW flight was canceled for mechanical reasons, I was put on a later NW flight that arrived after the last flight of the day to Tucson. After putting some pressure on NW they offered me a choice of either:

1. A rental car for the 110 mile trip (at my expense) and $100 in future travel on NW

2. A hotel room for the night and change my flight to the next morning (it was a nonrefundable penalty for change ticket)

I stayed the night and continued my travel the next morning at no additional expense. I can't say if my Platinum status on Continental Airlines made any difference on the resolution.