Uncle Jesse,
Like you, I have been there many times. Unless I see a lot of activity on the surface, I always start with a Woolly Bugger, and I change it every 15 minutes, starting with Black then to Green then to Brown. I go out and start a slow troll, using an intermediate line, looking at the bottom of the lake, the shore, any activity, bugs in the water and in the air, husks from hatched bugs, and I change my trolling speed and my retrieve pattern. Usually within an hour or so I should have taken some fish.
If there is activity on the surface then I start with a Parachute Adams until I see what they may be taking. if I can't see, then every 15 minutes I change flies, using a Renegade then a Griffith's Gnat. If there is surface activity and no fish takes a variety of flies then I switch to a soft hackle fished from a floating line and fished just under the surface, figuring the fish are taking emergers.
Larry ---sagefisher---