In Toronto, check out Sew Sisters. It is on Chesswood Ave.
www.sew-sisters.com Also, you might want to check out Lens Mill. They have an outlet on Orfus Rd.
www.lensmill.com should get you their website. The stores are huge with lots of 'other' stuff, but lots of fabric too.
Be ready for sticker shock in Canada. Our prices are significantly higher than the US, and in Ontario, you also have 13% HST added. Painful I know, but there are also bargains out there.
Were you planning on going as far as Kitchener/Waterloo? There is a great farmers' market called St. Jacobs, every Tues, Thurs and Sat. Definitely worth a visit. There is also a fabric store at the market. And three km. from the market is the village of St. Jacobs. It has a couple of very nice fabric shops. One is Riechards (
www.reichards.com/) but I don't remember the name of the other. BTW, there is also a Lens Mill in Kitchener.
Hope you have a great vacation and find a few gems along the way.