Can’t decide which vehicle would be best for my situation

I don't know your kids, but I will say there is a near zero chance the Tahoe will survive to have the 9 yr old ever drive it. ;)

A gas 2500 has enough payload for whatever you would want to haul behind it or in it. (short of a large truck camper) If diesel, I agree with get the 3500. Lot's to think about in that choice, especially with the new gas engines coming out.