I saw this question on Cinch, and answered it there, but thought, "Hey, maybe I should post this on the blog!" [Not for nothing that I have two degrees!]
What are the top 5 things that best drive a client/customer experience with your organization?
This will vary by industry and type of client -- business clients want different things than consumer clients do.
You need to distinguish what is called "hygiene factors" from things that drive satisfaction. Hygiene factors (think lack of clean silverware) are bad when the minimum standard is not met. Exceeding the minimum standard (even cleaner silverware) does not make people more satisfied. So you have to meet the minimum acceptable standards for the business FIRST. If you have glaring gaps in these standards, it should be your Number 1 priority to fix these gaps.
Having said all this, I think it is safe to say that people expect to be treated with (1) courtesy and respect; they expect you to (2) do what you say you are going to do, and they expect (3) transparency in pricing (no gotchas, the kind of thing telcos are most known for). (4) Being easy to do business with is also a big one. Of course this means different things in different environments, but a lack of irritating policies and paperwork is a good place to start. (5) And appreciating their business is important for all of us. There are so many ways to show this -- by saying thank you, by showing loyalty to your customers, by solving problems when they come up.
I do believe if you really work at these things, your business will do better than if you don't. So I need to go look after my own clients now :-)