I'd probably plant things that looked well with red brick, that is pink and blue flowers, and silvery foliages.

The weeping cherry will cascade to the ground, and should be located where this habit fits. Most here get lopped or sheared back and thereby spoiled, because the people owning them are bothered by the branches approaching the ground. Probably many of them were bought for the flowers rather than the growth habit, a non-weeping cherry having been the preferred choice.

If you don't have a wall for a weeping tree to drape, a pond for it to form a backdrop to, or another situation where a drooping habit is advantageous it might be better to choose something else.

Cherry trees are also prone to pests and diseases.

I'd yank the clipped hedges in front of the windows the second day I moved in. Otherwise the shape of the lot would lend itself to a nice sweeping lawn with flanking informal beds. Without the hedges you could look out onto quite a pleasant garden scene.

If you are lost for ideas and want to beautify most of the yard maybe seek professional guidance.

So, the hedge is made of gardenias? How many plants form each hedge?

I love gardenias, but think they look best when allowed to assume a more natural form. What if you removed some of the plants to give them more space and stopped shearing them, but instead pruned to allow a fuller, more natural shape? Then put some low-growing flowering plants in the foreground. Geraniums need full sun to perform well.

The house does have a geometrically symmetrical formal facade which would seem to call for formal planting such as the matching hedges in front of it. But the informal outline of the lot shape strongly outlined by the sidewalk and the garage off to the side giving the total structure an asymmetric shape probably makes informal planting the best choice. A rectilinear formal garden in front of the facade would conflict with the curving outlines of the lot, as the clipped shrubbery does now. Better to partly conceal the geometry of the house facade with climbers and a tree or two, naturally shaped foundation shrubs rather than emphasize it with formal planting.

First of all, you have a great looking house and space to do something special with the front. Although you mention landscape design briefly in the description you mainly seem to want plants and flowers.
Neither of these are going to come cheap. If you seriously want some curb appeal rather then just a few geraniums planted here and there, you need to spend between $1000 and $1500 on a basic design plus plants. This isn't to scare you off, you just need to be realistic.

Here is a link that might be useful: yourenglishgardener

Don't be too quick to lose the hedge without thinking about what new issues may arise once it's gone. The slope drops off rather precipitously on the left side of the house, and the long formal edge helps to keep the house from looking like it will slide down the slope.