16:9 in general usage is pretty useless to be honest but lets face it, it's cool.
If you're planning on watching dvds on it then def use 16:9 otherwise trying to watch 2.35:1 movies is impossible.
Normally the screen will sort out stretching/cutting.
Watching 4:3 movies on a 16:9 screen really isn't too bad - you usually forget and have to try and find a circle like a clock to see if it's stretched or not
If you can afford the extra, I'd recomend widescreen.