Tartan in the Modern Home
Tartan reads as traditional, but it sits happily in a plain modern room as long as it is the only pattern present.
Pick one piece per room — a throw over a chair, a runner down a table, a single cushion — and let everything around it stay flat in colour.
If you want two, keep them in the same colour family and vary the scale: a large repeat on the larger object, a small one on the smaller.