Personally I wouldn't want WIFI at all if I had to turn it off when the screen is off. Part of the deal here is that WIFI is faster and more efficient. If I have to download updates etc and have WIFI available, it is generally better to use WIFI. If however I have to keep the screen on in order to keep the downloads working, then there is an added cost. What would be a smarter approach IMHO is if the radio would cease trying to connect if there isn't a network I've approved available after X amount of time. It can pop up every X minutes and check again, but if no network, it should shut down. This is essentially what Juice Defender professes to do, though it also professes to have location/learning based means to turn the network on. So while it may save some battery if you set it to turn off when the screen is off, you might as well never turn it on as far as I'm concerned.