For wood patterns, I take inspiration from plank floor textures; where any given plank may be lighter or darker than average. So, I might use three different shades of wood to create irregular “stripes”, simulating the idea that each plank/floorboard is a different piece of wood. However, this can be really difficult to keep consistent and not look like a random static-y design, so I often just go with a flat wood colour; usually mimicking whatever I’ve used for the upright supports.
For walls, I just mix up a variation on the “log cabin” look created by using two-block-wide stripes of a lighter and darker wood colour. To simulate really large logs I use a 2- or 3-block wide stripe with a single block wide highlight above it and a single block wide shadow colour below it; stack those up and you get a good impression of huge, chunky log walls (works equally well for horizontal or vertical logs.)