I should clarify that the above arial photo shows the shed on the other side of the yard. Alot of the trees on the right side of the arial photo have been thinned out and the shed is on that side now

Not sure how much height you really need, how fast. One thing to consider is that when you plant to the south, you may not get as much shade as you expect during the actual hot months, when the sun is to the north; and you may get more than you want in early spring and late fall, when the sun is to the south and you want your patio to warm up. Trees to the west-northwest are probably best for shading a patio in most of New England. Take a look at heptacodium - it's quite narrow and in fact is adaptable as far as the number of main trunks. A lovely and unusual tree, and because it flowers late, and has long-lasting, colorful calyxes, it looks good for a long time after the flowers fall. The exfoliating bark is interesting, and a well-grown specimen can look good even when the leaves are gone. It can be found relatively inexpensively because it's not especially hard to propagate and grows fairly fast when it's young. If you don't want messy flower fall, I'd stay away from cherry. Of all the cherries, I'd maybe recommend prunus mume, but it's not reliably hardy in your zone as far as I know. Stewartia is a lovely smaller tree, but prefers some shade. In your zone, it might be fine in sun - I have some in full sun that do well, but it's cooler here on the cape in summer, so you might want to check with your arborist or a local nursery. It can be quite pricey for larger specimens, in my opinion, but it's a great tree. S. pseudocamellia is the most common (and, most people think, the most beautiful) but some other varieties are narrower and might be better in your situation. There are some smaller varieties of katsura (cercidiphyllum) - one of the trees on my "must have" list. One, Heronswood Globe, only reaches 15' - not sure if that's tall enough for you. That's one of the most beautiful trees - no flowers, but really great foliage, lovely color and shape.

The Camillia I bought last fall is still hanging in there, but hasn't done well for me so far. I covered it over with a milk crate and leaves last winter, worried that it wouldn't tolerate the cold it's first season, after I planted it in the fall and not the spring. I don't think it appreciated having that milk crate of leaves sitting on it all winter, because it dropped all it's buds before they opened, then lost leaves over the summer. But it has been in the ground for a year and it still has some healthy leaves and I think I see a couple of flower buds starting to develop. This year, it's on it's own over the winter. I am still interested enough in growing them, to give it a different location if it is still struggling next spring. And I may order a different variety of Camillia and plant it in another location and try it again. I hope it makes it through the winter and starts putting on some growth next year. I think the biggest challenge in my garden is dryness and not the winter cold.

If you are willing to move one or two of the crape myrtles, you could replace them with a southern wax myrtle, which are evergreens but don't flower. You can use them as a hedge or as trim them up into a tree similar to a crape. They get to be about 15 to 20 feet tall and 10 to 15 feet wide (depending on the website you believe), grow pretty darn fast, and, as a bonus, are native. I have some in my yard as a hedge in hope of eventually obscuring the privacy fence behind us. I'm resigned to the fact I'll not get complete privacy, so I've lined up the bushes/trees to obscure certain well-used windows of the neighbor's house so they can't, for instance, see us eating on the patio. But they can watch me mow the lawn from their second story window all they want. Either way, though crapes are deciduous, they can be pretty dense even without leaves if you don't prune them much.