If you just want to cook it "day-of", I would suggest the following (skip the brine):
What kind of Salmon do you plan to cook? When I can get it, I prefer wild-caught Sockeye, King (Chinook) or Coho. I think Sockeye has more of that distinctively unique "salmon" flavor. Farm-raised can also be good, but tends to be more fatty and lighter in flavor.
Grill it indirect, or cook it on the WSM using a high-heat method (no water in pan) similar to chicken. Apple chunks provide a good touch of smoke flavor without over-powering. I've heard good things about Alder and Grape Vine, but I've never tried them myself.
Fillets can be laid, skin-side-down on a "pan" made of doubled heavy-duty aluminum foil, with the edges folded-up on all four sides. The skin will stick to the aluminum, and can be left there when the fish is peeled-off with a spatula between the flesh and the skin.
If the fillets are skinned - a grill basket works really nice (spray it with PAM / oil it first)
A smallish whole fish could be cooked with or without the head - i would stuff the body cavity with some sauteed onions and a little olive oil, salt, and pepper - then close-up the cavity with oiled twine or some sort of long metal pins. In this case, I would get the heat a bit lower, but not too low 300-ish, and give it a bit more time to cook-through.
Either way, I like to keep it simple - I place a few rings of raw onion on top if in the pan / on both sides if in the basket, salt & pepper lightly, then maybe drizzle with a little olive oil (just a tablespoon or two)
If your cooker is pre-heated, it should usually take about 15 to 20 minutes - check it in the thickest part, when no longer translucent, it's done.
If you want, you can make a sweet red wine reduction sauce or Hollendaise type sauce.
