With 6 people - forget the std Escalade or Yukon/Tahoe - you will need all 3 rows of seats and there wont be any room behind the third row for any luggage. However if you can get a Yukon XL or a Suburban then you will have loads of room for everyone and luggage.
The Traverse/Enclave/Acadia is not bad but room is still limited behind the third row but much better than the Escalade/Tahoe/Yukon.