What is good customer service?

As a former small business owner, I do not like to hover over a customer or be too pushy. I like to greet them, ask if I can help with anything and check back with them in a few minutes. I like to be treated the same when I go into a store (especially to be acknowledged that I am there), otherwise I walk out and take my business elsewhere. Do you like to be greeted, helped as soon as you walk in the door or to be left alone to do your shopping? What is important to you as a customer? What makes you want to return to a store?