Ethan, towing that boat with a FWD minivan is no problem. Logged quite a few miles with boats and jets skis up to 2500 lbs. behind a Dodge Grand Caravan 3.8 V6. Make sure you get a transmission cooler, either factory or aftermarket. The tight packaging of most minivans engine bays places cooling capacity at a premium. The DamChryco 3.8 V6 is a very refined "old technology" motor. It's a pushrod motor that Chrysler tamed in terms of overall smoothness, but it still has the torque of the pushrod motors of yesteryear. Pulls very strong on the low end, perfect for towing.
Trep, we had a tranny problem BEFORE I started towing with the '97 Grand Caravan....factory defect showed up at 4K miles. My sister-in-law drives that van now, and it's got well over 80K miles without any further issues since the tranny was repaired; it's a solid van and still looks close to new; my brother-in-law is a wash and wax fanatic. Later model years have better tranny history. We have a 2001 Town and Country now, don't tow with it, but it's solid at 45K miles.
Most minivans don't do a heck of a lot better than trucks when it comes to MPG. Our minivan gets abuot 18 to 19 mpg in suburban driving. My Sport Trac (4.0L v6) gets about 17.
There is no question, a minivan makes hauling kids so much easier. My wife laments driving one due to it's lack of curb appeal, but she would never give it up while still toting a youngster.
KIA does offer great value and an awesome waranty. The incentives on the Chyslers are always appealing. I particularly like the new stow-and-go seating features.
If the anti-minivan folks here scare you into looking at something else, consider an entry level Ford Explorer. It's actually very well equipped, has a good basic towing setup with the 4.0 V6, OEM coolers, and a hitch. It's one of the smoothest riding SUVs you'll come across, so it's easy to live with as a daily driver. I see them advertised for under $19K all the time.