Why choose native plants? They are already well adapted to the area, they tend to require less water than nonnative species, they are more ecologically sound (e.g., not an invasive species), they invite birds and butterflies to your property and help preserve biodiversity. Prairie plants can provide color from spring until fall and help feed birds even in the winter.
When I bought my home nearly two years ago, there was one mature tree on the southeast corner of the house, but not much else that could be called landscaping. Some that were present, I chose to remove as they were ugly (juniper bushes), diseased (cotoneaster) and poorly placed (Korean boxwood bushes).
It took a friend saying "why don't you plant native species" and my aunt, who evaluates land for the USDA, to make me to think about my choices for what to plant. I chose some plants without realizing they were not native: hostas (native to China), daylilies (likely from Europe), and tulips (native to the Middle East). My aunt suggested a basswood tree when I asked her what native species she would recommend. I did some research, decided I agreed with her choice and picked up Tilia americana 'Redmond' from a local nursery. I was very proud of my first planted tree.
I delved further into native plants and found a mail-order nursery that specializd in plants and trees native to my state. I ordered two blueberry species bushes, two Rosa blanda bushes as well as two native trees, mountain ash (Sorbus americana) and ironwood (Ostrya virginiana) as bare root stock. This order would make all the trees planted at my home native (the mature specimen is green ash).
How did I determine what species were native and what to plant? Much of native plant research centered on my local university's horticulture web site as well as the state Department of Natural Resources web site. These gave me information about statewide distribution, what are considered invasive species (e.g., Norway maples, which are overly planted in my city, are considered such) and size. Other sites like the University of Florida's Tree Fact Sheet is a great index of information on each tree including site requirements, longevity and any diseases that affect it. For example, my basswood tree was 40% defoliated by Japanese beetles, which find this species of tree quite attractive. Since the basswod is not much more than six feet tall, this was an issue.
Another great resource is the local university extension office. When I noticed spots on my rose bushes and described the condition of one of my newly planted trees, the agent had some bad news (the tree is dead because I did not water it enough) and good news (the leaf spots were treatable with a solution). There may be additional local resources such as a gardening club or a local nursery that carries native plant species in your city or state. I know there are a few places in my area that raise and sell praire plants and seeds. Consider making the choice for native plants in your landscaping. You may find you like them as much as or even more than many of the commercial plants.