Look for tables that have extra leafs. The pieces that go in and extend the table. You don't have to keep them in so you aren't taking up all the space in the room with a huge table.
I have a table from Ethan Allen that can seat 12 comfortably and has 2 extra leafs. I keep 4 chairs around it, 2 captain's chairs are on either side of the matching hutch and the other 6 chairs are kept down in the family room's storage closet. I keep chair covers on them so they don't get dusty and pull them out as needed.