According to Feng Shui, in Restaurants and Cafés round tables are the most favorable. Also at home.
Round or oval tables facilitate communication and have no corners you can butt to or which you have to sit next to.
Sitting spaces shouldn't be standing too close together, so that privacy of the guests is guaranteed. Too many tables attracts a lot of covers in a Restaurant or Café business which generates a lot of business sales, but if guests feel harassed by fullness, tightness and noise, they might choose not coming again.
Comfortable chairs and good air circulation are extremely important for having a great vibes set in place. Seats with backs to the wall and look at the door would naturally be the most auspicious Feng Shui choice.