Use a dealer recommended electrician for reasons stated above. I can't tell you how many times I've been cursed out by electricians "who've been doing it for 20 years" telling how my spa is broken, when usually the case is they haven't grounded their wires.
Anyways, I always tell people to have the electrican come out and run the 220v up to where you are going to install the sub-panel, if he has time maybe he will run it up to the the point where the tub is, but most times the electrician runs it up to the sup-panel then comes back on the day of delivery to run the last couple of feet and connect the tub. Usually they will fill the tub also to make sure everything is working properly.
Definately pick the tub out before you run the wires.
