I do know that if you can't wear everything you have at once, you have too much (except socks and undies). I do also know to layer, layer, layer. I just don't know how to best layer with the best pieces. I see rain gear as a definite, at least a top piece, but not sure of the best option there. Obviously, the lighter weight the better, but the whole idea is to stay relatively dry underneath it, so functionality would play a big part as well. This is planned to be an 8 day trip. Any advice on "Must Have" layers, brands, etc.? Keeping in mind, I'm a big girl. Has to be available in plus sizes.