Find the floor plan that works the best. Both gas and diesel coaches will get you over the mountain and to your destination. If you are the average RV owner that puts about 5000 miles a year on your rig, the cost of fuel should be way down on your list. If you need a 10K towing capacity, then there are NO gas Class A coaches that have this capacity so that makes your choice pretty easy. If you can get by with a 5K towing capacity, then your choices are open. Floor plan always it more important than anything else with an RV. You will spend more time living and sleeping in your coach than you will driving it.