I really like tying an orvis knot on the dry (something with some really good buoyancy like a humpy, hopper, or even a foam beatle), leaving the tag end 2.5 to 3 ft long, and tying my dropper directly to that.
I double up on bluegill almost daily, and the ocassional bluegill/bass combo (shown) while fishing my local warm water pond in North Carolina with that rig. I've yet to double up on trout though...