For the "typical" 18in fish in the TMA, I don't think the specific streamer matters that much, as long as it is in the 3-6in range in length. The best colors are typically black, olive, yellow and white. For patterns, a saltwater style bunny pattern is good, or a zonker style, or a big Zoo Cougar. The standard philosophy is to use black/olive in lower light, white/yellow in bright light. If you buy flies, look in the saltwater section first.
If you are targeting the really special giant holdovers (and who isn't?), it might pay to use a big jointed streamer. I have used articulated Zoo Cougars with great success in the past, but myriad patterns exist.
The real key to streamer success is how you fish the flies. It is generally better to cast across stream or up and across and strip perpendicular to the current. Use a density-compensated 200gr line and a short 0X fluorocarbon leader, about 3ft long total. The strikes are vicious. For better hookup percentages, I have been using stringer-style (wide gap) hooks like the Tiemco 8089.
As far as where the fish are holding, just remember that they are hunting salmon parr. The parr typically hold in the fast riffles, so the big browns hold downstream of those areas. Try fishing the moderate riffles and tail outs. Cover a lot of water. Most fish hit the streamer on the first 3 casts through an area. There is little point pounding the same section of water.
I use a 9ft 6wt TFO rod for streamers with a Rio 200gr DC line.
Go get 'em!