What can I plant at my backyard?

I live in Zone 5, Toronto, Canada. I have a long but narrow backyard. I am looking to create a natural privacy barrier that adds some shade and season-changing colors while keeping my hydrangeas (if possible).

Here is a drawing of my yard and the dimensions. The blue areas are patio stone areas.

Here are pictures taken from the left (where the shed is) and the right and from the middle (panorama view) of the yard. The 4th picture is where I need for the privacy barrier.

I have currently planted 6 limelight hydrangeas, one river birch, and 8 Annabelle hydrangeas along the fence. I am getting lawn replacement later this month or early next month. And I am planning to put in a vegetable garden on the right side where it gets the South sun.

Some goals I have in mind:

1. Shade - My house is East facing. It gets really sunny in the afternoon for anyone to enjoy the garden. I am considering adding 1 or 2 trees for shade. Preferably native, hardy trees that offer fall colors. I am considering putting October Glory (Red Maple) to the right of the birch tree, or can be vice versa. Not sure what other options I have... Any suggestion?
2. Privacy - I want to create a natural privacy barrier from my neighbors. I know I can plant cedars and let them grow tall... not sure what other options I have... Any suggestion?
3. Adding color - If I am planting something new, I would love to bring in a different color (or fall color).

Other notes:

1. Hydrangeas - Whatever the change is, I hope my hydrangeas can stay.
2. Cleanliness / uncluttered looking garden

Any answer is appreciated. Thanks a million!