Hi G.,
I would highly recommend Strong Landscaping. They are based in Warrenville: ###-###-####. We hired Chris Strong and his crew to help with landscaping around our new home and to install a paver patio in our backyard and they did a terrific job. They're reasonably priced, very easy to work with, straightforward and friendly. Chris is great with suggestions--he takes pictures of the areas you want to landscape and then comes up with ideas he thinks you might like--he is very knowledgeable about what plants and trees work in different areas. We also are doing our landscaping over a couple years. Last year we just hired them to tear out all the old stuff, plant one tree and install the patio. This year we'll probably be looking for more decorative grasses to fill in all the bare spots!
Best of luck to you!
p.s. A neighbor of ours saw the work they were doing and hired them on the spot to install a new brick walkway at her own house.