When calibrating a monitor (or big screen TV) you really need something to compare the results to - like a professionally produced printout. Or you need specific calibration test equipment that you position precisely in front of the screen. The problem is, and I have seen it over and over again with big screen TVs, once perfectly calibrated, the users don't like it. It is not "warm" enough, or too bright, or not bright enough, or the flesh tones are not pink or orange enough.
I mean, how do you know what shade of green the football field is supposed to be if you cannot compare it to the exact shade of green it is?
Then with computer monitors, people get them to display photos and videos just right, and then they don't like how text is displayed.
Another problem is many monitors will not let you fully adjust - especially when using a digital input with DVI or HDMI.
Finally, the color displayed is also based on the color the computer's graphics solution is telling it. So there are many many variables at play here.
I use
Video Essentials to calibrate Home Theater systems, but generally for computer monitors, I recommend letting the monitor auto-adjust, then just start tweaking until you like it, or for the best compromise.