Holy crap - thanks guys, some great ideas and suggestions here.
I should start mapping out a rough itinerary as I'm coming in next Thursday, but only for a week, so I'll miss Doors Open and the Toronto Islands will still be 'closed' or not in full tourist season. I may have to move my visits from mid to end of May to catch more stuff that's going on although that increases the likelihood of humid weather which is brutal for walking 10-20 km a day in.
I did catch the private ferry over to the islands in 2024, in fact was the only person on board which made taking photos easy. Overall it was a disappointment because of the time of year I think - pretty dead (but maybe better than crazy crowds?) and the greenery and gardens weren't at their peak yet. Also nearly everything was shut down except for a couple nice caravan type set ups and a bizarre Subway shack that only sold cookies and fountain pop... I'm used to tourist season being year round and it surprises me that a chain of nice islands directly across from a mega city can be so quiet and even have an off season. But the skyline views alone are worth it and I didn't go to the far side of the islands, so it's probably still worth another trip.

View of downtown from Toronto Islands - May 14, 2024. by
JohnnyJayEh, on Flickr

Runaway Cafe on Wards Island, Toronto. May 14, 2024 by
JohnnyJayEh, on Flickr

Toronto Waterfront - May 2024 by
JohnnyJayEh, on Flickr
"
sandwiches from Tutto Panino on Sorauren which parallels Roncy" - added to the list, thanks Niwell. One final complaint, lol - food can be hit or miss, it seems you really have to know the places locals go to and don't rely on social media/Youtube. I tried three different places for Banh Mi and a Vietnamese coffee and they all sucked and not one of them served an authentic Vietnamese iced coffee, bizarre. It seems with a high cost environment in Toronto a lot of places are relying on cheap quality, less than impressive service and sheer volume to make a go of it. That said it's on me to do a better job of finding the good/great places which are plentiful.
"On the topic of rooftop bars & restaurants with skyline views: the Writer's Room at the Park Hyatt is another good one" Thanks MonkeyRonin, always enjoy a good rooftop bar! And it's right beside my hotel which I believe also has a rooftop restaurant/bar of sorts, but not sure if it has much of a view. Ironically my friend's son is playing piano in the Park Hyatt lobby a day or two after I arrive and as part of jazz jam in a nearby club the night after.
"you can probably enjoy a cocktail at Aera, the bar on top of the main office tower of the Well." - thanks Hipster Duck, didn't know this existed. I find the Well a bit sterile, but the bar sounds like a possibility. I like hole in the wall places or a place with style that is still casual enough - like Leña which unfortunately closed not too long after:

Leña Restaurante - 176 Yonge Street, May 14, 2024 by
JohnnyJayEh, on Flickr
And yes, the skyline view Riverdale Park East was great, and even better was the return trip where I came across that park/farm, the cemetery and the cute church and I'll be damned, I felt like someone was watching me and I turned around and there was Jack Layton's bust smiling at me, lol. Pretty cool. As was Cabbage Town and surrounding area, fantastic, beautiful colours and the walk from Yonge at Bloor Street East to Parliament and into Cabbage Town is pretty awesome as well.

Cabbagetown - Toronto, May 15, 2025 by
JohnnyJayEh, on Flickr

Toronto Necropolis Chapel - May 19, 2025 by
JohnnyJayEh, on Flickr
Thanks again for the insights everyone - reading them and looking at the colours and views in my last shots has got me pumped about going again.