Assuming you're refering to carnal fun and not the herbal inebriants that Amsterdam is known for, but Montreal by far. Wonderful city, the adult entertainment capital of Canada.  Many options (use the TER search engine or peruse the MTL board) and with the exchange rate in favor of the US$, donation rates are fairly inexpensive compared elsewhere.  Stay in Old Montreal, pretty central to everything--restaurants, sights, public transit, and the city's massive underground walkway.