I like to look at bikes in department stores to see what is selling there - sort of like market research. Dick's has better bikes than Walmart and Walmart has better bikes than Target (which are awful). Depending on what you need and how much you can spend, you might find a suitable bike at either Dicks or Walmart. The problem is that if you're shopping for bikes there, you probably don't know what you need or what is good and what you should absolutely avoid. And no one at Dick's or Walmart will be able to help you. A good LBS will give you informed advice (usually) which is helpful. If you're just starting to ride, find one that is relatively light (under 30 pounds?) and that you find comfortable. Ride the heck out of it and let it tell you what your next bike should be.