Scott, I have had a Titleist ball fitting. Very informative. They ask you what ball you currently use. They let you hit it and give you stats on it. Ball flight, ball spin, angle of left or right you hit. From a Trackman device I believe. Then they recommend a Titleist ball to use and let you hit it. They give you the numbers. You can see how it improves your game.

I would LOVE to do a ball fitting someday... It would be cool to go through this process to see if i'm playing the right Titleist ball...

I did one a few years ago. Like Gabriel said above, it's very thorough and they use a Trackman and give you all your stats. Based on the numbers, they make a recommendation for which ball you should use. In my case it was coincidental that that the recommendation was the ball I was already playing--Pro V1x.

The staff that puts them on are awesome, pretty much like everything else about Titleist. They're always happy to talk about any questions you might have and they love seeing the TT bag tags on your gear.

I had a ball fitting earlier this year, the Titleist fitters took readings using trackman of shots with a wedge, 7 iron and driver comparing Pro V1 and X's. using the visual flight trajectory and the Trackman numbers they then recommend the best Pro V1 for you. they gave me two sleeves of balls one of each, to chip and putt with. They also had the full range of their other balls on the putting green if you wanted to compare them
I had been using a 2015 X up until the fitting, I have now changed to the 2017 Pro V1 now as I prefer the softer feel off the putter.
I was told they go through the same fitting process with the Tour Professionals using Titleist balls, the only difference is they also include readings from a 4 iron as well.
If you get the opportunity to attend one I thoroughly recommend it.