Strictly for towing, I would want every advantage that the 2500 Suburban chassis offers... stable rear leaf spring suspension, thicker material thickness of the frame, heavier duty rear axle, etc. The cost to "upgrade" to a lighter duty version in order to only gain 2 mpg fuel economy would never pay for itself in the short or long term, especially with the added cost of an extra warranty. Unless gas shot up to $10 per gallon.
However, for primary use as a daily driver, the loss of heavy duty components in exchange for the greater comfort of lighter duty, more car like hardware makes a lot of sense. I'll bet your wife is much happier with the trade... and as the old saying goes, happy wife, happy life!