I've done both....a lot.
I agree with MPond above says about the flat tow.
The advantages of a trailer have been well laid out too.
Trailers are a PITA to store (and buy). My LJ's still a DD, so flat towing behind an RV is still something I do several times a year...never a problem.
That said, a well set up Wrangler's at least 4500 lbs...and that's going to push around "a van full of people" pretty well....and more importantly than that, it's going to increase your braking distance SIGNIFICANTLY. Your sig shows a Liberty, and I don't know what those weigh.
It may be safest to have someone drive the Jeep, instead of flat towing....especially if you may encounter steep mountains, rain, and/or wind.
4" Currie springs/CA's, TR beadlocks, 35" MTR's, D44's ARB's & 4.27's, RCV & Superior, OR241, UCF TT