Currently, where I live diesel is less expensive than gasoline. This hasn't always been the case. More energy per gallon at a lower price. Seems like a no brainer. Diesel buyers will recoup their extra up front costs when they sell. If the buyer plans to keep their truck as a very long term hold then diesel is the way to go. All the towing advantages are an additional plus.
When I purchased my SUV I chose diesel over the gas counterpart. The diesel was actually less money (MSRP) but not by much. The diesel will save me approximately $1,300 per year in fuel costs (at current prices). In 10 years the fuel savings will be about 1/3 the original purchase price of the vehicle. Fuel economy shouldn't be overlooked if you like to put the miles on.