Here is another shot from my side yard, eventually this space will be fenced and either pool or a place for my kids to play football.

Here is a link that might be useful: view from side yard

Absolutely plant trees and shrubs! Try a nice variety so you get different colours and textures. Don't buy online if that's what you're going to do since the plants they send you will be tiny. Confession time for me - I buy a lot of my trees at Zehrs, Home Depot, Canadian Tire, Walmart etc. They are all doing vety well despite their humble pedigree. Last year I bought 3 japanese maple that were 6 ft tall for $19 each at Zehrs and last month We got a yellow bird magnolia from Home Depot for $80. I've scored purple leafed sandcherry and redtwig dogwood for $7 and limelight hydrangea for $5 and knockout roses for $5. You could do a lot for $1000. Here are my three suggestions - don't buy any tree that will grow too big, no more than around 20 ft, and have something for each season - witchhazel for spring, hydrangea for fall, carpet roses for summer, evergreens for winter etc. Lastly, make sure you have differnt heights. It willl be fabulous!

TNJ,
Carpet roses would look nice where the junipers are now.
They are pricey though. That is alot of ground to cover, but they do spread nicely when they get bigger.
What about your watering situation?
Is it possible for you to get a hose down that far in front of the house?
If you don't like the idea of roses, there are daylillies, they are great for hills and hardy once established. The possiblities are endless really.
If you don't like the color of the stairs, paint them.
i don't think they look bad, they draw attention to themselves and you might want that.
In the fall, you can buy tall evergreens for out back for privacy. They are inexpensive and I would start with 6 ft trees and mulch real good.
Congrats on your home, it is beautiful!
Remember, gardening really does take time. It will evolve over the years, but that is OK. Everything does.