Since I don`t have a boat and fish `em up` er a ways (heck even low on the Sandy) I run 8-12lb leader maxima UG(water clarity dependent, of course), one size up from that for main line. Primarily a drifter I still use egg patterns and other flies way up and down, eggs way down, spinners all around (chart/green dot is my fav.). I go 12 for leader with spinners.
I noticed ya asked about depth, which for bobber fishing is a good ? IF yer standing by the water, or asking about a specific hole. Same for plugs, just can`t say how deep from here without knowing a specific local. ALWAYS 1-2 feet off the bottom, or closer for any salmonid, 99% of the time. You might come to a big deep pool and see them suspended, and that`s the only time I would come up OFF the bottom.