dampair,

i like tying my trolling flies on tubes for a couple reasons. one, they are a little more buoyant tied on plastic tubes and wake easier (for the surface fishing). two, the hook is at the very end of the fly and those silvers just love to short strike flies.

as for colors, i'll just relate two color schemes that were very effective out at neah bay this summer. the first color listed is the bottom color. white, red, lots of silver flashabou, and green. white, yellow, blue, lots of silver flashabou with lots of blue flashabou over the silver. white, red, and blue has also worked for me... but the two previous seemed to do much better for me.

cb