Often it makes sense to finance a new home through the builder of that home. Builders (specifically those in Las Vegas) may offer incentives and claim great rates. However, buyers may end up paying for their decision over time. Some times, lenders associated with builders will charge higher rates because they have a buyer somewhat locked in to get the incentives they expect.
It's important to shop around. Make sure you at least understand your position with several lenders so you can negotiate. A good agent will be involved as well in the negotiation of the loan.