Tree question. What should I plant in front of my house?

Here are the details:

- I live in Portland, Oregon.
– Tree(s) will be planted in the strip (3 ft. wide) between sidewalk and city street.
– Looking for a great-looking tree that will grow to 25–45 feet.
– Would like a tree with smaller leaves that both/either flowers in the spring and has great fall colors.
– Would like to create some privacy between street and house so would prefer a tree that is dense with branches and leaves.