From a handling and general convenience viewpoint stay as short as you can tolerate ... floor-plan-wise ... and built on as heavy duty chassis as you can find for minimum worries on how much weight you might ever want to tow behind, or carry in, the motorhome.
The DW and myself and one small dog have been completely happy with a 24 foot Class C for years. It's built on the Ford E450 chassis so we have no concerns about how much we load it up. It handles and drives like a rock solid and stable van in all situations - due to it's heavy springs, stock front/rear sway bars, stock front steering shock, large brakes, and wider rear dually stance (than that of the new crop of narrow Sprinter-type Class C motorhomes).
On fishing trips it tows our fishing boat as if it wasn't back there. Otherwise we don't tow anything on RV trips because it's short length allows us to park in small campsites and park right at a lot of sight-seeing, eating, and shopping locations.
We like having our complete little self-contained home with us at all times. As appropriate and needed, we leave our little pet-person in the coach with the A/C running, or a powerfull 12 volt fan running, or both the A/C and the fan running.
