Begin with what the audience must read
Display selection is about legibility, not just screen diagonal. The furthest viewing position, the smallest text in the presentation and the width of the seating plan are useful starting points. Wide rooms may need more than one display so delegates are not looking across other attendees.
When projection works well
Projection can provide a large image efficiently where the room offers suitable throw distance and controllable light. Screen position, projector location and sightlines must be planned together. Bright room lighting or sunlight falling on the screen can reduce contrast substantially.
When a large display works well
Large-format displays produce a bright, crisp image and can suit smaller rooms, exhibitions, confidence positions and spaces where projector placement is difficult. Physical screen size and safe support positions can limit their suitability for a large audience.
Content and connections
Confirm presentation resolution, aspect ratio, videos, audio, presenter devices and connection types. Build in time to test the actual files. Where content changes frequently, a controlled playback laptop and operator reduce the risk of desktop notifications, missing fonts or last-minute connection problems.