When you move forward with the vignette, three things happen: (1) With limited expense, you’ve furnished one area to completion. (2) What you’ve chosen sets a style and mood to direct the rest of the furnishing. (3) You limit and define the size and placement of other pieces in the room, by process of elimination. Here are some other ideas for room-starter vignettes: a table in the hall (with it, consider a lamp, a tabletop collection, and hung artwork); built-ins or scaled furniture to fit in a window bay; a well-lit reading corner; seating near the fireplace; a large signature piece on the only unbroken wall; a grouping to play up existing symmetry (as between doors or flanking windows, or around a staircase).
You may not want a museum room, but furnishing in sync with the date and design vocabulary of the house is a shortcut to non-faddish rooms that “look right.” Your house is giving you clues, so take them. Seek out specialty suppliers that do reproduction, traditional, or adapted styles. You can, over time, acquire a few antiques to set the period mood. To fill in and assure sturdy comfort, rely on good reproductions or period-interpretive designs.