If there will be speeches or announcements, try to place the speakers so that they won’t have their back to anyone. Place pregnant, elderly, and disabled guests, as well as those with small children, in a location where they have easy access to toilets and other facilities. Don’t seat them at tables that will be removed to make space after the meal. Older guests will generally have poorer hearing and eyesight, so try to put them where they can see and hear any speeches. Don’t seat them next to loud music, as they are unlikely to appreciate it. Put children’s tables in the least favorable locations, they have better hearing and won’t be too interested in the speeches anyway.
Assigning seats or tables
Guests can be assigned to a table, where they can choose any seat, or they may be assigned to a specific seat. It seems that assigning tables is probably more common in the USA, and assigning seats is more common in Europe. Both approaches are valid. Which you choose is a matter of personal preference.