In the first picture, I think you'd be better off to coordinate a single shrub to the window, then plant the rest of the space with groundcover(s). The Hydrangea will become fine with growth, if trained into a small tree so that it doesn't overwhelm the walk. (This means periodically give it the ice cream cone shaping. Eventually, you'll denude the lower portion of leaves.) In the other picture, a 4'-5' deep hedge of hosta along the bottom of the fence would look good. and some relatively low groundcover that turns the two trees into an island. Or, don't continue the hosta for the last 5 fence panels and just use low groundcover below the trees.

What Patricia is trying to say is that your local garden center will sell the plants that grow best in your area. They may even be able to help with a plan. I can give you a list of my favorite plants, but if they don't sell them at your local garden center it wont be helpful. It is good to do plan that includes both sides. When you look at your house from the street, you see the big picture ( not one side) - all the plants should look good, together. To be most helpful on this site , it helps to know as much a possible. What is your zone, how much sun does this area get - 1hr 3hr ( does it face N, E ,W, S) What is the soil like. And how big is the space. Do you like flowers, evergreens........

What direction does the house face? (You can look on an online mapping program if you don't know.) That will influence the amount of light and therefore the plant choices. If the beds across the front of the house aren't at least 5' deep, you want to make them deeper to accommodate shrubs so that you won't need to do extensive pruning. 6'-8' would be even better since most evergreens aren't tiny plants.

Though I said I can’t suggest plants, I do have some thoughts to throw out in case you haven’t already had them yourself. You mentioned landscape design cost @ $1500. - have you checked costs for a just a planting plan design with you buying your materials & DIY labor? Some larger nurseries do provide that limited design service ( or can recommend someone) &, especially if you ask, will give you a discount if you’re buying most or all of your plants from them. I got a 10% all season long discount from a nursery after showing them my professional landscape design plan for both hardscape & plant material so they could see we were starting from scratch with a new home. We were installing the plants as DIY because I wanted to choose them, swap some from plan, control costs & I like doing it. You said your neighborhood has other terraced yards - have you / can you look at them up close & take pics of planted layouts & of specific plants that appeal? I Googled images of terraced front yards in Atlanta & there are a lot of them to look at for ideas. Your comments “assuming we’re looking for cub appeal...”. & “Should I be mixing in evergreens...”. Absolutely, yes on both counts! Planting evergreens provides year round appeal and structure. I would explore true dwarf conifers, spring flowering shrubs, some very low evergreen ground covers (think elfin Thyme), spring bulbs - how beautiful scattered through those layers! I would avoid a row of tall plantings that would completely hide your stone foundation that is a decorative feature. Be mindful of mature size of any trees you plant as they may change the light received on the terrace & shade out your plants. I don’t know if your front scape was completely shaded before the loss of your huge tree but I bet your light has changed. I’d look at a smallish flowering tree to place closest to house. All of these flowers & textures may be a happy medium between your idea of English garden look & wife’s idea of 3 season blooms & foundation color. I’m leaning towards your wife’s idea. I do admire English gardens but not for a front yard -too many flowers & too winter bare. With your property, it sounds like you have space for one somewhere, right?