I had a 1700 Nomad for awhile, and while I like the bike, I had a hard time coming to terms with the gearing, especially 5th and 6th, where it felt like there was no power. The bike is well-appointed, and comfortable, and handles well. My gas mileage averaged about 41--42 mpg but I can't comment on 2-up gas mileage, as my wife rides her own bike. I can say that it handles well with a passenger on board, and it doesn't seem to make much difference to the engine whether you're 1 or 2-up.
Now for the (extremely) downside. I pull a Bunkhouse camper trailer. The Gold Wing does a superb job of doing that. I figured the Nomad would, too, so I put a trailer hitch on the bike. The first time out with it, we went to Osoyoos, BC, Canada for a rally. I never could get the trailer to settle down and be stable behind the Nomad. No matter how I arranged the weight in it, it was always sashaying side to side to one degree or another. Made me really nervous. Then, coming to a stop on a slight downhill grade, as soon as I touched the brakes, it nearly went into a tank slapper and was headed for the ditch no matter what I did. Fortunately I was able to muscle my way out of that before it got really bad!! I decided right then to get rid of the Nomad ASAP! The other issue was gas mileage. There was no power going up long hills and I had to gear down. On some of the longer, steeper hills, I was in 4th gear with the throttle pinned to the stop and I could only manage 40--45 mph, and my gas mileage indicator let me know that I was getting a whopping 17 mpg on the expensive premium gas. YIKES!!
That was with a stiff headwind. Minus the wind, I was rewarded with gas mileage in the low to mid-20's, and upper 20's to 32 mpg on the level with no headwind.
I say all of this to let you know that while the Nomad 1700 is a fine motorcycle, there are some negative sides to it as well. I think if Kawasaki re-thinks the gearing it could transform it into a much more tractable bike. I wouldn't recommend towing a heavy trailer like a camper trailer. The Bunkhouse weighs 325 lb. empty, and when I've weighed it in travel mode, loaded up, it tips the scales at 500--550 lb. I suspect that towing a small cargo trailer would be OK and have a much smaller penalty on the gas mileage. With the price of gasoline being what it is these days, that is a major consideration. If I were going for a larger displacement cruiser, I'd consider the Victory Crossroads or Cross Country before the Vulcan. A little more spend, but much more and better motorcycle, IMO.