The good news is that spotting at YYZ
has become a lot more friendly as of late. The authorities have backed down considerably in their quest to kick spotters out of certain areas. As was mentioned above, 05/23 is under construction and currently limited to approximately 7,300' so they tend to only send smaller aircraft out there.
Spotting for the 06's/24's isn't as good, but you can try the places mentioned above. The other good news is that the 33's/15's are used more frequently now, and these have great vantage points. For 33L activities, the infield, or then the hills just west of the runway are great. If 15L is being used, then at the north end by the Skycharter hanger is also very nice. You just have to drive around and explore the area a bit, and you will begin to know the places that you like best.
Other than that, get an airport job with ramp access, and the spotting will improve immensely.
"it's kind of like an Airbus, it's an engineering marvel, but there's no sense of passion" -- J. Clarkson re: Coxster