The botanic gardens on South Park usually have a nice showing outside, although I didn't get a chance to see them last year. I've heard Niagara on the Lake has some lovely gardens, but I've never made my way up there. There are usually some nice displays just across the border in Niagara Falls, Ontario along the falls in the park.

Tracy

If you are a member of any of the plant societies - North American rock Garden society, hardey Fern Foundation, american Rhododendron society, whatever, and attend their local and national meetings you will see a lot of really great private gardens. One garden I am dying to see is Frank Cabot's "Les Quatre Vents" in Quebec. Stonecrop is another of his and now I understand he has one in New Zealand.