Can anyone recomend a Satnav system for oldies???

My mother-in-law wants to get her hubby a satnav system.
Now these are people with practically no computer skills!! ( got a phone call to ask me why the computer wouldn't start up when they put their email account details into the start up screen of a library computer)
Mobile phones and dvd recorders are kind of like rocket science to them.

I know nothing about sat nav systems myself as my hubby seems to function perfectly as one .

Is there such a thing as a satnav system which is so easy that a granny/grandpa can use it. I am rather reluctant to recomend one to her as I think it will get taken out of the box switched on and then put back in when they can't figure out how to get it started.

I am happy to take on the apdating bye computer as long as it is only required once every few months.

Any suggestions?