Hmmmmm, I was going the smaller/lighter route, and especially the upright ADV route until I got a significant other who likes riding with me 2 up, at which point I went out and found a used ST1300, prefarkled. I love the bike but it can certainly become a handful at fully fueled weight with a weeks luggage for 2. That said I am really, really, really, looking at the new R1200RT in Alpine White. Almost 200 lbs lighter than the ST1300 fueled, pre-farkled from the factory, suspension, heated seat, and ergonomics very good for 2 up riding. So yes this bike is a bit smaller/lighter than the ST and will be my next 2up long distance ride.
In fact those of you at Colorado Springs might just see an alpine white one with NC tags out there... it just depends upon the outcome of some projects...