x1 on what apgambino said---the king of rear seat space is the Ram Mega Cab. Although the Mega Cab is not offered in the Ram 1500, it is offered in the Ram 2500 (3/4-ton) version, which also comes with a coil spring rear suspension. Coils tend to give a smoother ride than leafs.
Going to get a lot of subjective input here. If you're gonna spend $40k-$60k on a truck, I'd suggest personally driving (and having your kids sit in the rear seat of) all the truck offerings from Nissan, Toyota, Ford, Chevy, and Ram. You might be surprised what jumps out at you---both good and bad. FWIW, had a friend's wife make their final truck decision based on the location of all the cup holders--lol!