Round tables may still dominate for weddings and events. However, the demand is shrinking as brides and event designers opt for rectangle and square tables. Depending on the size of the square configuration, you can seat 10-12 guests. Tablescapes for round and square tables follow the same rules.
Small or narrow elements on the table must fall under 12 inches in height. Small but wide elements should be less than nine inches. Tall upright elements need to clear the table 24 inches. Typically when dressing a round table you design in odd numbers. So, you'd never put four candles on a round table, you'd put five. That's where things diverge a bit. Tablescape elements ought to be even-numbered. This is to prevent the eye from being distracted. It keeps things uniform. The brain is trained for symmetry, so don't interfere with odd-numbered elements at a square table.
When you are going for height on a table and you want a statement piece like the lamps in this photo, use materials that are clear like acrylic. This allows light and vision to pass through the decor without having to look around things. If you find your guests moving centerpieces to talk to each other, that is a huge red (and expensive) red flag.
Keep your tablescapes beautiful and appropriate, which will translate into designs that never hinder your guests from communicating across the table.