I think all the stupid little laws that hurt absolutely no-one are a load of crap. As for proper laws though, marijuana should be legal, and prostitution should be legal. However, prostitution should also still be heavily regulated, and made so that the people choosing to work as prostitutes are protected, forced to undergo regular health checks, etc. Making it a legal industry (because let's face it, it'll never be stamped out, and what about those who choose it for whatever reason anyway?) would help to reduce the level of illegal pimping and forcing people to work on the streets, and would help protect those who do choose it. As well as helping to effectively 'out' the ones (pimps mainly) who are actually doing other illegal stuff (drugs, extortion, human trafficking, etc.). And would help ensure discreteness for those people who do see prostitutes, given that really I don't see it as all that bad, provided it's all consensual (which it would be in a regulated industry). The only problem I see with the clients of prostitutes is when married men or women go to them, and cheat on their partners, which is just wrong in the same way that any other form of cheating is wrong...
I'm rambling on a bit here, but I just felt like getting my views across there. Anyway, as I say, I think marijuana and prostitution should both be legalised. Hell, look at Denmark. Go To Amsterdam. Look at their crime statistics and stuff like that, and you'll see just how alright things are in a place where those things are perfectly legal...