In shady areas best bet is impatiens...sunny, but not too sunny, go with begonia in white, pink or red. Geraniums in pink or red are taller and almost always do well in pots or in the ground. I recently did both and they worked out well. But if you put them in a pot, it has to be a pot with a whole in the bottom for drainage or the leaves will turn brown and die if you over water them.
There is no NO maintenance, you have to water them, especially impatiens.
Lots of people in Kirkland use Petunias. They grow better in Kirkland than they do in Bellevue and they come in lots of colors. They give you the same color splash as impatiens, but take to sunnier areas better.
Marigolds are bright and almost impossible to kill :) But aren't as pretty as the other varieties I have mentioned. Use them in between other flowers in little bunches.
Take a walk around, especially on your street where the house faces in the same direction as a sun reference. See what does well in your neighbors' yards. don't look across the street though...keep walking up on the same side of the street, or you will be buying plants that do well if they face in the other direction.
If you go to any garden store, or home depot even, they will only have those that are "in season" and primrose is one of the few flowering annuals that is hardy enough to plant before Mother's Day.
Most important: mix in some good nutrients to the beds before you plant. Your local nursery can tell you which is best for your needs. Then mulch on top after planting. Get a mulch that looks good with the color of your house. Water well the first couple of weeks.
Good luck! Send some pics!
For instance, if the entire yard is grass then you probably would want lots of colorful flowers. But size and height may me important to add some texture. If there are no shrubs in the yard a couple of large pots (either tall or wide or both) brimming with flowers may be better than a single row of immature (small) flowers.
I would start with Mary's suggestion below and take pictures of the entire front yard and consult with at least 2 or 3 nurseries.