A few years back I planted a good sized potted fruitless crabapple tree. It has grown well and I enjoy it year'round due to it's shape. Growing up (usda zone 4) I remember a small front yard down the street with the most stunning red maple (gorgeous!) and nothing additional. Very Striking. Good luck - this is one of those good problems, no? :)
Fhionn

A few years ago we bought a crabapple tree for the garden. It was a Makamik crabapple (not sure of the spelling.) In the spring, it has very nice burgundy foliage, then the flowers come out a nice pink and very fragrant! I'm actually thinking about getting another one. Another nice tree is the Ivory Silk Lilac tree. In our zone it seems to be very slow growing but very nice. Marg

I just purchased an Ivory Silk Lilac, which is good to zone 4, and is very adaptable to soil. It grows to aout 18 feet, but has the most amazing flowers in May. Something to consider. :)

In the front of my house I have a Japanese "bloodgood" maple. It is gorgeous! Leafs out in April and holds its leaves very late into the fall (here at least). Leaves are maroon-red. Just not sure if they are hardy to zone 5.

You should consider a Kousa Dogwood. Beautiful white or pink flowers(depending on variety)in spring, red fall colour, grows to about 30 feet tall and 20 feet wide. Very beautiful tree. Kousa is more disease resistant than the native florida varieties. Google Cornus Kousa and you'll get lots of info and images. I finally planted one for Mother's Day after pinning for it for years. I love it!