Welcome fritz. I bet there are lots of trails up there that most of us don't know about. Nice area up there.
Mike, I did that hike a couple summers ago. Its definitely an all day thing. We left Glacier Point before sunrise, and didn't get back until after dark! Of course we did climb Half Dome and spent about an hour to an hour and a half up there. Very beautiful and breathtaking! I think the route we took was approx. 18 miles, so take PLENTY of water. Sorry, got
Again, welcome to the board, Fritz!