Why wouldn't you just forward them a link to the driving directions page? You lose all the functionality of the awesome Internet we have in 2010 by sending someone a static map. Anyone who can receive that would be in front of a computer connected to the internet, or if they are on the go, would be on a smart phone with internet access so they could look it up themselves. Might as well just carry around a paper map.
Unless you want to be a doormat like that guy in the commercials whose friends call him to ask him for driving directions and movie show times because your phone lets you browse the web while you're in a call at the same time. Let your friends look up their own directions.
I typically send all three. I send the link for the driving directions, I send my own summary which makes sense to local people, and a screenshot of a map, with my scribbles on there. "There's this landmark, here's where you turn, this is Xyz Lane which you'll see on your left just before the street you turn into, so be ready when you see it, here's our house on the left. If you're coming from the south instead of west, this is where you'll be coming from." As far as I know, no one's ever gotten lost this way.
I can't speak for the others, but I have lots of friends who have phones with no data plans (probably 90% of my friends, in fact). I can't send links to their phones, but I can send them screenshots via MMS. It's come in handy on many occasions.
Unless you want to be a doormat like that guy in the commercials whose friends call him to ask him for driving directions and movie show times because your phone lets you browse the web while you're in a call at the same time. Let your friends look up their own directions.