Suburban/XL hands down. Love my Tahoe, but the LWB for the kids, dog and grandparents popping in and out during the year is worth it every time. Road trips, camping, just getting around town and the ride is great. My wife came from an Odyssey after 10 years and was nervous about the length, parking, turning, doors, etc...
Other than her recent curb rash, she wheels that big land yacht with style, she backs it in, loves the features, the room (2nd row buckets) and all the bells and whistles the LTZ offers. Get the XL and you have the bigger motor already in your favor and that extra cargo room that the SWB cannot even compete with.
I don't think you will regret it for 1 minute. Just my .02.