Vans are awesome towing vehicles. Based on pretty much identical frame and drivetrain as pick-ups, they tow well.
We've been towing our 2004 Keystone Springdale 37BH with a 2006 GMC Savana 3500 6.0 liter 15 passenger van. Currently has 205k miles, but it never towed before I purchased it. The manufacturer's tow limit for the van is 10,000 lbs, and our trailer weighs 11K or 12K lbs. Our total weight on CAT scales is 18,200 lbs.
The trailer is 39' long, and our total length is 60'. We're a bit over the limit but I could care less. The main safety device is the gasket between the driver seat and the steering wheel.
I use a weight distributing hitch. I also have an anti-sway bar but in 2000 miles I never used it. The trailer always follows straight and never wiggles. Perhaps it is due to larger frontal area of the van, but I never had any swaying issues.
The van has been equipped with a 10k lbs hitch, trans cooler, towing mirrors and a brake controller. I can comfortably maintain up to 70mph on a highway. We get 7.8 mpg when towing, I think it's fantastic.
However, when we were in Asheville NC area, it's an extremely hilly terrain (9% grade), our combination could only maintain 35mph in the rightmost lane and also began to overheat (no electric fan here, the fan is viscous coupling on water pump), so I turned both interior heaters on full blast and it helped a lot. The uphill was for only may be 10 miles, so no big deal.
We're a young family and we have two little daughters (2 and 1 y.o), so getting a van was a no-brainer. I removed the extra seats and added a conversion van power sofa. You can't beat the room inside, the kids can sleep on the power bed, go potty, have lunch, walk around, etc.