thats pretty interesting, when I got the wife's escalade and was shopping denalis, finding a bench was a nightmare, they actually swapped the bench into it for me and pulled the buckets. I don't think you'll have a hard time finding someone who wants your bench if you go that route. The suburban has buckets, since I usually have the third row out its a 4 seat truck, the caddy is the planned baby mover, and since the 3rd row will be folded, and a child seat a 3 seat truck sounded really really stupid. My only regret was getting a shorty, I have a feeling we'll outgrow it in a few years if more kids come our way, but the esky was enough of an adjustment for her from her maxima. Even though these days she even says your truck rides nicer than mine with 130k miles, why? I said wheelbase honey, that and you stab the pedals like a crazy soccer mom.
On a side note, I"m pretty sure there isn't a max tow package for the denalis, they're all setup to tow, might be an option for you if you can find a deal on one. (the stupid caddy on the other hand doesn't come with an integrated brake controller, have to use a pigtail and aftermarket)