I went from a Excursion pulling a TT to a crew cab with a fiver. Passenger space is an issue and I only have 2 kids and a dog.
Since you have not purchased yet give your Suburban more consideration. Agree your Diesel will tow much better and your family can fit in a crew cab, however a family of 6 will be cramped in a crew cab especially as the kids get bigger.
Passenger space is a concern on longer trips with a family of 6 in a crew cab.
I have had my current combo about 3 years and we still miss the passenger space of my prior Excursion.
