All I can add for the showers at YYZ is that be prepared to wait! I usually take the red eye from YVR and then have ample time (I think) to get in and it seems during the week I have experienced a line between 7 and 10 people, it's a great service so you can feel fresh and get on the with the day after an overnight flight but too bad there are only two showers! Oh well I still think the lounge in T1 at YYZ is great and very comfortable to be in and the shower's (from the outside at least!) look very inviting! (Unlike the US departures lounge in YVR which is starting to look a little tired! but still a massive improvement to most american lounges!) And for the arrivals lounge at YVR I haven't seen any indicators of where the arrivals lounge is and there is no indicator of it on the AC website!

Happy Travels