Some guidelines...Learn Wright's Wrules.
These will save you and your customer lots of grief about table sizes.
Take this page to a quiet place. Sit down. Commit to memory...
Wright's Wrule of Wrectangles:
You will need one foot of length for every soul you intend to feed.
Eight people = eight feet. Ten people = ten feet.
Wright's Wrule of Wrounds is more difficult:
You may seat as many people at a wround table as its diameter in inches divided by eight.
And Wright's Wrule of Wrooms:
A big table will not fit in a small wroom.
*And please remember, oversize chairs wrequire more wroom.