Dining rooms and entries are where crown molding does the most work per linear foot. These are the rooms guests see first and linger in, and they're usually small enough that a larger, more detailed profile is affordable.
Formal dining rooms, foyers, and entry halls — especially homes with archways, which give the molding something to wrap and articulate.
Arches. A curved run has to be cut in segments and eased around the radius so the profile appears continuous, and that's genuinely difficult work — it's the detail that separates trim carpenters who do crown occasionally from people who do it every day. Where dining room crown meets an adjoining space, the transition gets planned so the two rooms read as intentional rather than interrupted.
One day for a dining room; entries usually the same visit.