I am not particularly concerned about electric power consumption.....I can afford to pay my electric bill. I just feel that it's a good idea to turn off my machine completely (whether its a desktop such as an iMac or Mac Mini or a notebook such as my 15" rMBP or my 13" rMBP when I know I will not be using the machine for a while, whether that be overnight or for a few hours. Especially in the summertime, weather conditions can change quickly and I really do not want my machines fried because they were on (even if sleeping) during a violent thunderstorm with lightning that manages to strike in just the wrong place.
Seriously, it only takes a few seconds to get the machine going again,and what's a few seconds? I am still delighted with the difference in speed between my current machines with SSD and my former machines with platter hard drives -- in the old days I'd get the iMac started up, then go into another room to make coffee or do something else.... With the current rMBPs equipped with SSDs, well, they're up and running in nothing flat.