I'd probably suggest a walking trip, starting from Yonge and Bloor, heading west through Yorkville, south at Avenue (past the ROM, you can stop by if you wish), passing through the University of Toronto Campus, down to Queen Street, and then heading West. You'll pass Much Music, the youngsters of the city, you'll be able to choose whether to hang North on Spadina to catch China Town (and Kensington Market) or continue West to see the new gentrified Queen West. You could also plan to catch a symphony in the area at the TSO if you're into that. Lots of small kitchy art galleries along the way, plus nice coffee shops, etc. You won't get a flavour of Toronto if you plan to visit an institution or a theme park. Walk it, eat, and walk some more!