When I've DMed, I typically do it around a coffee table. While the players are on couches and chairs surrounding the table, I usually just sit on the floor. This lets me use the table itself as a DM screen. With all the area under the table, I've got enough room to lay out notes and leave a couple of books open, thus negating the need for most of the quick-referece tables. And when I need to roll dice secretly, I usually roll on the table and cover the die with my hand as it comes to rest.