Good posts. YYZ is my home airport and I try not to use the MLL for some of the reasons described above plus the lineup to use the elevator and lineup to check in. If I arrive at the airport in time, I use the PP lounge instead even though they are also not much better in terms of offerings, I can get in/out quickly. I do use the MLL International lounge.
When away from YYZ, I would sometime use the MLL but normally use other options. In SFO I use the Amex lounge, in LAX I use the TBIT lounge. In YVR I use the MLL as there are no better options for domestic.
Food offerings in MLL have been rather sad but hope for some improvements given the recent AC announcements. They also need to reduce selling MLL access and also perhaps not provide it gratis to ACV customers who upg to J for $200.
Lastly they need some sort of 'concierge/SD' in the lounges. We have the agents at the entry desk and we have the cleanup crew. Would help with someone with some level of authority that can walk around the lounges tactfully fixing the silly stuff like kids throwing food, drunken louts, people on speakerphone skype calls, etc. I know we cannot legislate good behavior but a gentle reminder would help improve the experience for all of us. I have had on very rare instances a 'manager' come up and talk to me in the lounges. I used to enjoy this lounge benefit but now its almost inconsequential other than getting a couple of quick drinks in before sleeping on a red eye.