Here are a few pics of my Prewar Toy Train table. The table is all vintage Lionel track and switches. The outside loop is O72. Followed by a Standard track loop to accommodate two trains. Inside is O gauge loops that can run either two smaller circles or one loop. My table is 7x12.
Hope this helps. Bottom line this is your table/layout. Have fun. Be happy with what you build. Everyone has different interests, skills, space availability, time and money to devote to this.