You need to think about a couple of options that range outside what you may compare to the typical bulb or annual.
Ground covers - immediately after reading your question, vinca or periwinkle came to mind. It's a lovely ground cover and it's hardy as well as craves mixed sun and shade. The flowers are very pretty. If you fertilize it correctly and get a good flowering variety, you'll have a lovely big blue/purple bloom (about the size of the old dollar coin).
shrubs - depending on the variety, hydrangeas are fabulous. Many sizes and colors. They put a lovely smell in the air when blooming in summer.
-The Peony is a wonderful full luscious flower. Lots of varieties, colors sizes and demands. HOWEVER -- they need at least a half day of full sun. They will not thrive near a house or under a tree.
- Roses are easier than most think. They need about 4 to 5 hours of sun daily when active. Again, lots of varieties.
- Lilacs are very easy. Wonderful smells and they are fabulous against fences. They do need 4 to 5 hours of direct sunlight daily to bloom.
- Forsythia is just amazing when it's in bloom. It looks like all the limbs shooting up are on fire. They grow well in partial shade. The down side is that it looks like it's half dead the rest when not in bloom. I'd get it if I had a large yard. I love these when they are in bloom. They do need to be cut back every year.
Don't discount trees
Dogwood - This is so pretty when it's in bloom. It's a spindly tree, but well worth result
Fruit trees - peaches, apples and some others put out really beautiful blooms
Go on-line and look at what Zone you live in. Most nurseries will tell you what zone a plant can survive. It will indicate light needs as well as size and type of plant. Usually there are pictures and other essential growing information.
Once you pick some varieties, you can research them a bit more. You can learn more about what pests and other issues the nursery may not reveal.
I personally like shrubs because they are the most carefree and really produce.