There's a time for adventure and a time for being smart and planning ahead.
I peek ahead at turns and destinations when I need to be somewhere on time that's new to me. E.g. doctor's offices, or meeting someone to look at a car, or getting to a party.
Countless times Street View has saved me searching for parking, or finding an office building that would not have otherwise been obvious, or missing a poorly marked exit... which in this part of the country can mean driving quite a distance before being able to turn around.
Another nice use of Street View I found was when home shopping 2 years ago. The pictures posted by real-estate agents don't always tell the whole picture about the neighborhood around the property you're looking at. I would always grab the street address if possible and check out the surrounding houses. Sometimes, a nice home on a real-estate ad looked very different when you saw the neighbors...
Using Street view in that way saved me quite a bit of trips.