I did mine through AVIA and Video Essentials and thought my setup looked great. That was until I had Gregg Loewen come in and work his magic. I was and AM amazed how good my picture is now. (Even my wife was amazed and she is one of those women who thinks that TV is just pictures and words)
There is a big difference between 'tweaking' the display with Avia or DVE, and a professional calibration. The calibration is done in the service menu for your particular display. Most displays 'out of the box' are calibrated to be too bright, therefore they run 'hot' at higher than 6500 Kelvin. By getting the display calibrated correctly, you can prolong the life of your display.
After professional calibration, you can always go to the user menus and adjust to your liking using Avia or DVE. A lot of people get put off by the price of a calibration--I know I didn't want to spend $500 as I was originally quoted. When the price came down to $250, it was worth it for me.