One thing to take into account is the fact that diesel prices are rising faster than gasoline prices. New federal pollution standards are going into effect that has a lot of refineries scrambling to build new units which will refine diesel to a much cleaner burning fuel. And of course, the oil companies aren't going to dip into their record profits to pay for this upgrade, they are passing it on to good old Joe Diesel. Fuel economy is kinda negated when you're paying $.30 more per gallon (at least that's what it is here in MT)

The positive about the diesel powerplant, imho, is the fact that a cummins, or a powerstroke or what have you, isn't really broken in until it rolls 100k on the odometer. 300k is, in most cases, pretty easily attainable, and the rest of the truck is usually falling apart well before the engine.

On the flip side, diesels stink. And they run a lot louder than their gasoline counterparts (although the newer model years are a lot quieter than they used to be). And occasionaly, in extreme cases, diesel will freeze (or gel) and that REALLY sucks. I know this from experience.

That being said, if I were in your shoes, with the same plans for my truck, I'd get the mega cab 3/4 ton with a 5.7L Hemi. Plenty of hauling power, good powerplant.