Finding a contractor can be a hard road sometimes. I have had great luck with the local homeshows though.
Contractors of all types attend with a lot of their portfolio in tow. You get to vet multiple contractors at once.
You can also check with the local Construction Contractors Board when you've identified candidates. This will allow you to see how many complaints, etc have been lodged against them. In Oregon you can even check the status of their license and Insurance.
This is how I found my roofer as well as the company that did my gigantic driveway and retaining wall. Companies I might have never found otherwise.
I would personally skip Home Depot or Lowes for a project like this. They just sub-contract to local people anyway and I would rather work with them myself. The issue with the sub-contract is that you have no control over who actually comes to do the work.
There is certainly something to be said for having a large company to back the work, but from my perspective, I find that in general, the bottom of the barrel tend to work for my local Big Box stores.
Find someone who has had similar work done and get a recommendation from them.