if you have 4 kids and are only doing day trips and want to off road- go with the suburban. That's what we have and love it.
i completely agree with KTM. My wife and I have four kids, aged 10 -16 and our 04 Z71 suburban has been wonderful. we have owned it for nearly five years and it has been, by far, the best vehicle for our family. We have had mini vans, smaller SUVs, full sized trucks, as well as a tahoe prior to the suburban and none of them have been able to match when the suburban has been able to offer our family (the tahoe was the closest, but lack of cargo was it's downfall). Great towing, power, safety, as well as cargo capacity & seating capacity. Ours seats 8, so it's perfect for us. As kids get older, they need their space from their siblings - stuffing three teens/pre-teens in one row, even if it's a suburban, is less than ideal. just got back from a trip to disney land last weekend and the suburban sailed through the trip and the kids were not on top of each other for seven hours straight.
off road, it has proven to be a capable performer and has even surprised me on a couple of occasions with what it was able to conquer. There are (hopefully) some serious mods in it's near future which will give it even more ability, but even if those mods don't happen, I am satisfied with what it can provide in that category.
Just make sure to remember what ever you decide, to balance out what your dreams are for it, with what its day to day reality will be. For us, that meant finding something that was a good platform for a handful of dirt trips each year AND a dozen family (paved) road trips each year in addition to being my daily driver. We have been extremely happy with our choice.
Hope this helps...