I've been obsessing over this issue this entire Spring. I had a fit last year, didn't change anything, but this year I am having neck issues. I'm 6'4" and ride a 61 cm frame with a 130 stem. I've tried a 120 stem, tried a 140 stem, back to 130 stem and I finally did something I didn't think I would have to do. DUM, DUM, DA, DUmmmmmm, I went nuclear and flipped my stem up.
I know, I won't win any Hot or Not contest and my bike doesn't look as cool as it did. However, my neck pain is gone and I am much more comfortable. I haven't had neck issues before and I tried to concentrate on my form and my saddle is the correct height. I'm not a racer, I'm an endurance rider and I have a 140-mile charity ride coming up in June. I guess my advice is comfort is the most important thing when it comes to cycling and find what works best for you.