recommendations for travel destinations?

i have never been travelling; i ve never really been anywhere. i live in vancouver, bc (canada), and am hoping to go for a bit of a vacation on late may early june but i cant decide where to go. i was thinking london, england, for more of an adventure, or seattle if im feeling a bit conservative. any recommendations of other places to go? id be going with a friend, maybe 2. im 19 years old if that means anything. im not so inclined to go to "typical" vacations "hot spots" ie. cancun/bahamas/etc. i want to go somewhere where i can see a bit of culture, gain maturity, and maybe even work my way to become worldly?
so thanks for any input in advance!