well, wherever you choose to go, make it your chosen location. As dynos will vary on readouts from location to location, pick one place and stick with it. It'll help the consistency of your results and the tuner will be more familiar with your vehicle, which will help the process considerably.
I'll probably be taking my car to Morgan, as I only have two drive wheels
I'm less concerned about peak numbers than I am about percentage differences across the powerband when I do my tweaking.