I was in a very similar situation to you a year ago, and I replaced my Tahoe with a lightly used GMC 2500HD diesel crew cab. I couldn't be happier... I'm getting better fuel economy on my commute and towing with the diesel, it's nicer to drive, and with 2 kids and 2 dogs having all the space in the bed is great. Plus, I can now fly up mountains without sounding like a rod is going to come through the hood, and there's nothing like having an integral brake controller and an exhaust brake to make stopping smooth and controlled.
