To catch big trout consistantly you really do need to fish for them. That basically means hunting them with big streamers. By big I mean 4 inches long and longer. Some of my streamers are over 7 inches. IMHO, the manner in which the streamer is fished as well as were and when is far more important than the specific pattern. Having said that, many very goog patterns were already mentioned: big buggers, Zoo Cougars, bunny flies, etc.
For the past few years I have been using a lot of Kelly Galloup's Zoo Cougars on a sinking line. Big browns are predators and to an extent, teritorial. One thing that I like about what Kelly teaches is that big browns very often do not hide in the kind of structure that you would ordinarily think. More and more we are finding big browns, over twenty inches, away from the traditional structure and in a few feet of water near drop offs and ledges.
To hear Kelly talk about his tactics go here, http://www.askaboutflyfishing.com/speakers/kelly/kelly.cfm . It is well worth the time to listen to this if you want to start hunting big browns. This stuff really does work.
One final thought though. Of all the fly fishing techniques, chucking big streamers is the most intrusive way to fish. These techniques may not be the way to go on a crowded stream. Not only do you cover a lot of water, you will also put all the fish down for a while. If the stream is crowded, find the fastest, heaviest water there is and work those big streamers as deep as you can through it. Oh yeah, fish short, heavy leaders, 1x.
