Not drugs, but rather the so-called oldest profession - prostitution. I'm speaking mainly of the US because I'm ignorant of laws in other countries.
I say yes. It's a business transaction between two consenting adults. I don't see how this is different from going to a bar, picking up someone, and then sleeping with them the same night. Maybe the bars are against legalizing it since it would cut out the middleman.
And of course, you have the benefits of eliminating the black market - safer work environment, freeing up of law enforcement to worry about real crimes, etc.
Like drugs, the legalization of this wouldn't lead to my participation, but the government shouldn't criminalize it, in my opinion.