Tahoe/Yukon will probably last longer....
I've got a 2007 Yukon and other than little quibbles (like the hydraulics on the tailgate glass going out and having to replace ball joints at 60K miles) I can't see it breaking down or even aging any time soon. It drives great on the highway and with 4x4 and BFG All Terrain tires I get about 16 MPG highway. By comparison my sister drives a 2010 Buick Rendezvous - the Buick version of the Acadia - and hers looks like it's 10 years old. Her seats are all ragged out, the carpet looks like shag and it just feels old (I'm sure her two kids have had an effect). Also, the Yukon doesn't have much room behind the 3rd row seat but the Rendezvous has virtually none.
Another bad thing about the Tahoe/Yukon is removing those 3rd row seats. It's insulting how heavy they are (80 lbs each). This is a $50,000 car, fer cryin' out loud. When the ever-so-shitty Ford Expedition has had power folding seats since 2005, GM has no excuse. I'm sure the upcoming 2014 model will fix this.
This post was edited on 1/11 at 9:49 am