First of all: I´d take at least 2 cylinders for 2-up touring.
And I´m a Suzuki man, so from that list, I´d go for either a GSF650 Bandit* (inline 4-cylinder) or an SV650S (which is a v-twin; the space is not very good for 2-up but it can do it, and the engine is a peach). But whether you like an I-4 or a V-2 engine more, is your personal decision, on that one I cannot help. Usually I prefer a V-2, but that´s just me.
Too bad there ain´t a DL650 on that list, because it has basically the same engine, but (a lot) better space for two, and would probably be my #1 choice. The SFV650 also has this engine, but it´s a naked bike, and doesn´t offer much space for two.
* At least in Europe we also get GSX650F, the same technique as the Bandit, but with a full fairing.
Do note, that with Suzuki the U-models are restricted, and there´s a difference in how that is done technically. Generally bikes with FI (fuel injection) are better off when restricted, because it is done with a different ECU (engine control unit) and it lets the engine run just like a full-power engine, until it reaches the legal limit, so for example in town riding, you may not even notice that it is restricted. With carburated models, there are several ways to restrict them, but often they´ll feel restricted all the way thru the rev range. Might actually make a big difference especially when loaded 2-up.
I used to be a Honda-man in my previous life, though, and if you like the big trailie style, the Transalp ain´t a bad choice either. Too bad the newest FI-version (XL700V) isn´t on the list, because it´s more punchy than the 650 or especially the 600 (both carburated models).
All bikes mentioned above have proven to be about as bulletproof as they get, if maintained properly.
Sorry I´ve never been so much into cruisers myself, but I´m sure someone else can shed some light on them as well!
Hope this is of any help.