I wish there were. I grown to prefer watching Netflix on my Wii and I like to go to sleep with a movie playing. My 360 is set to go off after 6 hours of inactivity (which is too long, but it's the smallest time they had) and my PS3 is set to shut down after 2 hours (which is what I chose but is often not enough time--I'll be watching a movie and it'll just shut off). No such setting on the Wii, as far as I know.
I'm pretty sure that if you leave it on for 6 months straight, it'll automatically shut down at some point, though.








