The Toronto Collection
While these books don't form a strict series, they are all set in the same area of Toronto and some of the earlier books' characters and locations do make appearances in later books. You wouldn't completely spoil your reading experience by picking them up out of order, but you would definitely find spoilers of how the earlier books end! To avoid that, start at the beginning of this list and read down. :)
If you'd like box sets of these books instead (cheaper!) click the 'Box Sets' link in the menu to learn more.