This past Thursday I had the opportunity to get a fitting with Jason @ Titleist Thursdays (Golf Canada Calgary Centre).
I have seen a lot of fittings (working in a pro shop for 4 years) and this was a thorough as you're going to get.
I was fit for 718 AP3's comparing them to my 716 AP1's. It has been a few years since my last fitting, in the past I was always a standard lie, turns out with old age swing has changed and I should be 2* up, which is the only major change.
Then I was fit for the 917 D3 Driver compared to my 915 D3 9.5* after trying 4 or 5 different shafts I ended up with a Aldila Rogue M"AX 65 (Stiff) shaft a 8.5* head with a draw setting. We also changed my 915 do a draw setting from standard, as my miss was a fade.
With the left over time Jason looked thru my bag and made suggestions about gapping of my wedges.
Sometimes it's just good to see the trackman numbers. I had my questions answered about ball flight and spin rates; I think the numbers have reassured me that I am playing the right setup, and the fitting has giving me the numbers to upgrade in the future.
I would highly recommend getting it done.