The term the "Wow factor" was well described by Michael Hyatt. He said that it's the gap between expectation and what you actually receive.
Going to an after hours care center here are my expectations: comfortable, quiet sitting room with a TV and some magazines, I expect to fill out a lot of paperwork, wait for about 40 minutes before being called to the back where the doctor will appear and disappear sporadically with long waits in between. They will give me a diagnosis and a prescription and i'll leave.
I recently visited a different urgent care center and was blown away by the service I received. The waiting room had huge fish tanks and water fountains, a child's play area, and free coffee. The receptionist took us immediately, filled out our paperwork for us, and sent us directly back. We were sitting with the doctor within 8 minutes and had her full attention for a good 20 minutes while we figured out what was wrong. Within a half hour, we had left with a solution to our problem, and a fantastic experience at the doctor's office.
Was all that necessary? Maybe not, but because they exceeded our expectations, we were super grateful, happy to refer them, leave feedback, and promote them. We now drive an extra 25 minutes when we're sick to visit this same establishment.
Seek to provide more value than people are expecting, give them the opportunity to be "wowed". It will create satisfied and loyal customers for your business.