I guess I would say lite. 4# for Lake Michigan Perch and local lake bluegills fished with 5.5' rod spinning gear. 6# for walleye with a longer rod when fishing bait.
My only experience with steelhead has been 25 yrs. of fishing, drift fishing from shore, in Michigan. I have come to rely on 8# mainline with a 6# leader, fished on a 10.5' rod. Fishing from the bank, I've lost plenty of fish when they've ran so far downstream that I couldn't pursue, hooked a few that broke me off on the initial run (awesome), but all in all I would say 8/6 works fine for me. Speaking of Michigan, perhaps some of the older members here may recall some of the published articles in S.T.S. about Dick Swan and his "noodle"rods. 13' fiberglass buggywhips designed to fish 4# with in some cases (dead of winter) 2# line. These guys hooked plenty of fish but if they were lucky enough to actually land the fish after a belabored and time consuming battle, the fish could not be released: it was exhausted. The fish was absolutely "terminal" if it was July and the fish was a Skamania summer run. Consequentially, IMO, I haven't seen a "noodle" rod on "the river" in a very long time. I guess that is a good thing.
Regarding salmon in the salt, I've only been fortunate to fish Neah Bay in Sept 01 and 02; the only times I've fished Washington. I did notice that line diameter mattered when jigging for silvers.