I live in Maine and fish lakes almost exclusively for brook trout, landlocked salmon, and lake trout. Lake trout is mostly trolling tandem streamers on fast sinking line. We have good mayfly and caddis hatches and I catch many fish on dry flies and emergers. I use mostly a 9' 6 wt. I keep two rods rigged in the boat, one with a floating line and usually a tandem rig of a dry fly and an emerger of whatever is or is most likely to hatch, and the other with a sinking line and a tandem rig of nymphs. When the caddis are hatching I sometimes use a floss blow line (described by Gary LaFontaine in his book Fishing Mountain Lakes). It is nothing but dental floss. The wind lifts the line and the caddis imitation daps on the water. Obviously, you need some wind to do this right. I don't cast streamers much, but on some ponds they work really well. I use the same rod and sinking line as for nymphs.