I have always done my own designs, but if I was looking for someone to design for me, I'd ask to see at least 2 examples of jobs they have already completed. Any decent landscape firm will be able to provide you with references that you can visit. Ask if they have an example with similarities to your job. Fairly recent jobs would probably give you more information about their current style and workmanship than older sites, but older sites might give you an idea about how their planning works out over time.

The guys at Beavercreek Nursery know their plants, but I am not familiar with their landscape designs. I think they are hardworking and honest, for what that's worth. They don't have a large staff, and I wonder how they'll tackle a larger job.
Finally, whomever you get, spend a lot of time before hand thinking of everything that could possible go wrong. Every single solitary time I hire an outside contractor, there are always loose ends I haven't considered or gone over before the job. Ensure they have detailed plans for cleaning up any worksite. Ask if there is a possibility of any changes or damage to existing areas. An example would be tire tracks through your yard. Take a good look at their contract. Do they give you an absolute fixed price or are there provisions for overrun? Can they give you a firm deadline as to when the job will be complete? Basically, just check them out as good as possible and try to think of what could possibly go wrong. If you visit some of their previous work, ask the clients what they would change if they had it to do over again.

Check your phone book and call in a few. There are many out there and they all should give you a free once over. So go thru all of them then make your choise. Good Luck.

You're not going to get a really thorough plan from someone for free. They might give you an idea, but they're not going to come out and spend the day with you going over all the details for nothing!

Personal recommendations can also be helpful! They can save a lot of wasted time interviewing people that you won't be interested in once you find out they don't do a good job.

Who's had someone, from the Knoxville or Oak Ridge area, do a really good job on their landscaping? Or, has anyone seen a really super landscape job somewhere in this area and know who did it?