same side of the table. if you have two kinds of chairs, have the chairs that are the same face each other. for example, have the same seats on the left and right of the table facing each other. and then also have the same chairs on the top and bottom of the table. if you have three or more kinds of chair, just follow the group rule.
if your table is circular, you have a bit more freedom with chair placement. your furniture will still look great if you don't place the different chairs in groups. you can also arrange the chairs like you would with a square or rectangular 