I went to Amsterdam when I was 17 with a friend for 5 days and smoked so much weed, I came back with a stutter, I mean, I couldnt even string a sentence together, I spent morning, noon and night in the coffeeshops. Before I went, I made a list of places I wanted to visit (non-weed related) and in the end, only ended up going to Anne Franks house but I had to leave half-way through because I was so stoned.
The coffee shop I went to was called Smokeys, didnt really venture far from the hotel so cant give you any advice in that sense......but go the Magic Mushroom Gallery - I bought some mushrooms and made tea but it didnt work, though I think it was done to me rather that the shooms.
Anyway, what I wanted to say was.....

When crossing a road there - be careful! Its so easy to get knocked over, with cars going one way, trams going the other and hundreds of crazy cyclists everywhere!