Depending on the height and width you want, look at the various panicled hydrangeas such as Limelight, Quickfire, Bobo and lots of others. The smallest ones mature at about 4’ tall and wide and others get bigger from there. You can often get ones trained to tree form. They are sun tolerant in New England and cold tolerant to z 3, don’t need a lot of extra water, and bloom for 2-4 months depending on variety. A lot of floral mass for the space they take up. They progress from chartreuse to white to pink tones, with different cultivars spending different amounts of time in each phase.

if you look this direction from the house, consider adding evergreens for winter interest.

Blueberries have small spring flowers, fruit, and red fall foliage if it is at least half day sun.

i have no idea as to critter resistance.

What zone are you in, since New England is a fairly large area and ranges from z 4 to z 6 with a few zone 7 areas.

i wouldnt plant in august ... just hold your pots until sept ....

there are a number of things called butterfly this or that .... which do you have ...

is that mulch or rubber pellets?? .. is there landscape cloth under ???

i had a lot of trouble with black mulch in hot sun ...

I’m in zone 6. The butterfly bush is a Buddleia 'Miss Molly. I have black mulch and no cloth underneath and I think it’s making the garden way too hot.

I definitely want to add flowering shrubs that will get tall and full. Do Lilac bushes do well in full sun?

Yes, lilacs do well in full sun. They are glorious for 2-3 weeks of the year, but not much to look at the rest of the year. There are some types that have occasional rebloom, but they have smaller flowers that don’t look much like traditional New England lilacs.

I was thinking of using full sun white hydrangea or limelight to line the fence and provide more full coverage and height. Then some sort of smaller perennial in between the hydrangea and closer to the front. I really like the look of the Sedum, which will be pink. Any other suggestions of what I can add in between the hydrangea? I will also be switching to a brown mulch next year.

Look at rhododendrons in the height range you want. They will provide winter interest so you don’t have to look at bare twigs and the fence in winter. They will provide spring blooms as well.

One comment about arrangement. It sounds like you might be considering alternating hydrangeas and another shrub. I am not a fan of this and would suggest that you several plants of the same kind before changing to another kind. So for instance three to five Limelights with Rhodies or lilacs framing them and groups of lower shrubs or perennials in front of them.

PS You can get a few bags of natural brown mulch to add a light top coat now if you want.

We have dwarf Korean lilacs and they are actually prettier year-round than some other varieties because they have cute, delicate foliage and a nice growth habit. I don't know what would be native in MA (I'm in IL) but you might consider incorporating some native perennials. It will reduce the work for you as they'll grab on and take root and be no bother. A good nursery should be able to advise what is native for your area and point you to some plants that fit you preferences. A bonus is they often bring butterflies and pollinators to your yard. Our bee balm also attracts hummingbirds.

Agree with switching to brown mulch. We like "fines" - meaning finely shredded. It does a better job of keeping weeds down but still lets water soak through.