I keep 30 to 50 windows open at any given time, and I am on the computer many times night and day, so shutting them down is a rare event. I don't know what it costs to keep our three computers running 24/7, but I don't think it is that much compared to the use we get out of them and that it is one of our few expenses we have for business and pleasure and don't mind keeping them on at all times. I would like to add that they are all energy star compliant, so they shouldn't draw much power in enery saving mode, and we don't let them hibernate either. Two desk tops and one small laptop. I think all three use less than 100 watts when in energy saving mode.
Dan