At the confluence of effectiveness and simplicity is the mighty Hare's Ear. Here is a riff on the old standard, which will liven things up at the vise and on the water.
Big nymphs have two jobs: entice fish and get the entire rig to the bottom. The Flow Stone does both.
Scuds are an important food source for trout. Whether you want to add a hot spot (as demonstrated here) or try and match what you're finding in your local waters, you'll be able to use this basic pattern as a jumping off point.