This is two seperate questions - one for sales and one for service.
For Sales:
If you could change one thing on the spa line you sell, what would it be and why? (Better lighting, Deeper tub, Placement of controls, Etc...) Lets avoid FF vs TP
For Service:
What is the most common type of service call do you receive? (Operator error, Cloudy water, Leaks - I hope not, Etc...)