If the interior was too small, why did you buy it? Cherokees were a low cost SUV that were passed by the modern minivan/"SUV" that are being sold now. It was one of the last real SUVs. SUVs were not nice to ride - they were utility vehicles. That being said, my Cherokee does exactly what I need it to do. It rides nice, decent mileage, and can carry a few people. Jeeps are easy and cheap to maintain. Use aftermarket replacement parts (there are A LOT of them out there) and you'll be happy with the Cherokee for quite some time. If you want a cushy, roomy, nice riding car: buy a minivan. If you want an SUV: buy a Jeep (except the Liberty).
Easy and cheap to maintain, utilitarian design, classic look, abundance of aftermarket parts. The straight 6.
Build your Jeep. Shop the internet for retailers who sell everything for the Cherokees. You can make this Jeep into anything you want or can afford.