Yukon XL or Burb, period. Especially if you are packing kids. When I take the family camping (wife unit and 5 kids + chocolate lab), they like to camp in comfort and we use EVERY SQUARE INCH of our '01 Yukon XL. When I go out to mine for gold I can fit my completely assembled "3 Keene dredge, finishing equipment, coolers full of beer, tents, etc. in the back of it.
When and if anything goes wrong with it, parts are readily available and for the most part, inexpensive. The motors in any late model Chev/GMC is hands down the most reliable power plant on the market today. And they are easy enough to work on that a reading level above the 6th grade, basic metric tools and a chiltons manual will fix anything. And the amount of aftermarket modifications on the motor is RIDICULOUS.
A mid 2000 model can be had at a really good price on the market. Make sure you go with the 6.0 liter, the 5.3 is a great motor but the 6.0 does much better when it comes to towing and the rig is heavy enough to begin with. The only thing I would suggest is that you have an independent mechanic inspect prior to purchase. There are a lot of these on the used car market and most of them have been driven.....A LOT. Mine is an '01 and has 110K on it ad its considered low mileage for the year. Most I have seen for sale recently that are around the same year are pushing 200K or well over and beat up.
Long story short, they are a great vehicle and great for the family. If your chitlins are younger, make sure you get a DVD player in it. I had one put in before a road trip with all the kids and bluetooth headsets........it was the quietest road trip we ever took. Worth every penny I spent on it.