Open plan designs often include shorter hallways, which is preferable for ease of movement. For best results, plan for additional hallway width at a minimum of 42 inches to best accommodate a variety of life stages. This allows easy passage especially for anyone using mobility or medical equipment. Wide hallways also provide easy movement of furniture and new appliances.
Altering hallway width may involve moving or eliminating structural walls, so plan accordingly. Modifying hallways also tends to affect most / all of the adjacent rooms, which can make a simple renovation much more challenging.
Make sure that doorways are also at least 32 inches wide minimum, although 34 inches is preferable. Also be sure to verify opening clearances on either side of all doors meet ADA requirements.