The idea of weakening Enkidu though sex failed completely. It was a stupid idea when you think about it.
Enkidu is the ultimate alpha male. Whenever he is near a human village he is followed by beautiful women, each wanting children that share Enkidu's strength and intelligence. So when Gilgamesh sends out prostitutes to entice Enkidu it's just a typical day, and does not delay him for more than five minutes.
Should Gilgamesh taunt Enkidu, calling him a coward? Or impress Enkidu with the power and grandeur of his magnificent city? Or show him the ease and comfort in a city, make him soft and weak? Or do something else?