Think about circulation
To be able to flow from one spot to another without getting 'stuck' will make using the space more enjoyable. Resist the urge to get pieces that are too big to 'maximize' seating, and make sure you have good distance between main furniture pieces so it's easy to slip in and out.
Add a divider if you want to create more formality
Formality of open spaces can vary from completely casual & comfortable to a place suited for entertaining. If you want to dress things up add a divider such as a paravant or back-sofa table to have a slightly more formal space.
For smaller spaces consider a circular dining setting
If your space is small a circular dining might make more sense to maximize seating without making it feel overcrowded.
For longer or larger consider rectangular or large dining settings
A rectangular dining table and living arrangement is more fitting for a a long shaped room.