1) Complimentary bar service.
2) Workstations where you can plug in and use dialup internet access, as well as have the use of a telephone with complimentary local/toll-free calls.
3) Complimentary light snacks.
4) Lockers in the bag/coat room. It is nice to lock everything up and be free to roam without the burden of all of my stuff. I usually travel alone, so without these I'm forced with either leaving my things unattended or dragging them into the restroom, etc.

I have been in airports enough times to have seen all I want to see. Now when I visit a new airport, I tend to wander about for awhile.