Montreal: Old Port and Old Montreal have tons of character, street performers, cafes. Dont miss Jardin Nelson on Place Jacques-Cartier for amazing crepes! The back patio is charming. You can climb up the clock tower by the river for nice views. They are great places for walking around and enjoying and nice day.

i would say Byward Market for Ottawa, it's got loads of shops and the entire area is full of everything. I woudl also recommend the museum of civilization if you're interested in canadian history or if they have a really cool exhibit going on. I've been to Montreal, but can't remember where we were exactly except that the top of Mont Royal is amazing.

In Montreal, Rue St Denis, Rue St Laurent and Rue Mont Royal. On Sundays see the Tams in Mont Royal park (East end) and Picnic Electronic in Parc Jean Drapeau. In Ottawa the market area is good and the original beaver tails shop also if you are a fan of douglas adams try Zaphods night club for the Pan galactic gargle blasters.

Montreal's old town is pretty cool and Mont Royal has great views.

La Banquise on the Plateau (google it, it's there). Gotta have some kickass poutine in Montreal!

It depends on what you're looking for. End of September, most of the street animation is gone in Montreal's Old Port. On the Plateau you'll find cool bars and restaurants and libraries and musics and ... In Ottawa, wait a few months and go for skating on the Rideau Canal ... miles of ice and fun and entertainment.

Given your style I would say the market is best. Ottawa has two main areas for clubbing, which is Elgin street or the market. I can't remember the name of the street in the market, but have someone tell you where the Brig is. That cluster of bars is a good place.