I agree with other here: sit down is more formal, and works well with small groups. I think it gives the reception a more classy feel. However ... 110 people? No, I think buffet would be far better for that many. We had about 100 people at our wedding and did buffet. It worked well. Some people just aren't that hungry, would rather mingle and talk (or drink), and buffets facilitate that far better than sitting at a table for an hour or more, waiting for all the courses of a sit-down meal.