This can vary by dealer as much as by brand. Sundance, for one, pays for exactly what is says in the warranty- parts and or labor, depending on the spefics of that repair. It also says that some dealers MAY charge a trip fee.
The dealer I got my Optima from didn't charge the trip fee. The dealer that took over for them when they stopped selling spa, does charge the trip fee.
Ask this question to any dealer that you are considering doing business with.
Other spa brands may vary, etc....