Memory table and Cake Table Size

I'm just wondering what size tables you got for cake tables (round) and those of you that had memory tables (also round). My cake is relatively small (only 50 people) so bottom layer is 9 inches and stand is 12 inches. I'll probably just have some votives around. I wasn't sure whether to go with 30 inch or 36 inch. Also, same question for memory table...I'm having 3 photos (4x6) and (5x7) with one sign (5x7) and small votives. Any input is appreciated. Thanks!