We have a land line and I have a cell phone (acquired when Princess Royal was in school for emergencies). We at one time had 3 cell phones, but Prince Albert never turned his on and the Princess Royal never could find hers, so cell phones aren't really that great of a solution for us.
One thing that I have bitched about to our carrier, is that they cannot serve us with a cheap disposable phone that I can give my kids when they are away from home. If I want my kids connected to us, then they have to carry a phone that, either is part of our "plan" or that we can buy cheap, but expires it after a month.
This one thing is a major issue. I have to buy a cheap assed phone AND a cell card, to send away when the kids are out or allow them to take one of our fancy phones with them.
Either way, we would not even be thinking in this way, if we were still tied to a single mainland line. The simple fact that we are able to send the kids away with a disposable phone in their possession that they can use to call home (and we care very little if they lose it) if they need to, means just that much more personal security and so much less worry.