YOU SAID:

A good speech should be like a woman's skirt: long enough to cover the subject and short enough to create interest.

INTO JAPANESE

良いスピーチは、女性のスカートのようなする必要があります: 主題をカバーし、短い十分な興味を作成するのに十分な長さ。

BACK INTO ENGLISH

Should be like good speech is a woman's skirt: to create enough interest in short though, and covers the subject enough.