We all get the streamer bug pretty hard in the Fall and with all the chases and aggraessive grabs really whats not to like about it? The trend in the last few years amongst streamer guys is using the biggest fly possible to target the biggest fish in the river. Now there is nothing wrong with that and the pay off can result in a monster trout but sometimes it pays off to focus on the smaller size streamers as well.
The typical streamer fishing that i see on our area waters usually fairs better early fall with the smaller streamers (sz. 4, 6, 8) and later into November is when i seem to do better with the double, triple, and quadruple articulated baitfish imitations. If you really look at the size of most minnows, sculpins, and baby trout in the streams the first ones to get gobbled up are the little guys. They are also easier to throw on a six weight all day rather than pitching the 8, 9, or 10 weight all day.
Line selection can be a huge difference in your grab rate going up. First off dont be afraid to pull streamers on a floating line in the shallower rivers. The lower madison for example has been producing some awesome streamer grabs in the shallow water and most sink tips would just hang in the moss. Also dont be afraid to combine some dead drifting with your fast retrieve strips as well. The longer that fly stays in the water, and more important the strike zone, the better.
For faster deep water you'll do better with a sinking line and from a boat i'm a big fan of a line with a fat shooting head on it just to help make casting easier and not take forever to strip in all your slack to recast. Airflo's Streamer max and Scientific anglers Wet Tip express are great examples of this large shooting head followed by a chunk of sinking line. A lot of the times if your just banging the banks from the boat you can strip in the line to the shooting head and simply roll cast it out for a quick easy 30' cast.
Use heavy tippet 10#, 12#, 15#, and 20# are all great choices. Any smaller than that and you might break off and any heavier than that and you can risk your fly line break in half since most fly line are built on a 20# core. I found this out the hard way this spring when my streamer i had attached with 25# test got snagged in a root ball. I pointed the rod and pulled back half of my fly line.
Soon the really big boys will get crazy and we can bust out a musky sized fly but for now don't forget about the "normal" sized streamers.