Here in the US the common perception is bigger is better.
As I suspect you know the F700 and the R1200 physical dimension are almost identical...ie the length of the f700 is as long as the r1200. (it think the F800 is slightly longer than the R1200) It does weigh about 50 lbs less. And the seat is lower and can be much lower with the low suspension model. I think that might be important to you and your wife.
If you are to ride dirt and paved roads there is NO need to have a tall bike...there are several reason why a low bike is better.
the R1200 certainly has more power, but the F700 is more than adequate...note it has more power than 75% of the Harleys on the road and those bikes, alone weight 600-800lbs. It has more power than the old R100 1000cc airheads.
The F700 burns considerably less fuel than the R1200.
Now that the F700 is available with ESA, which I highly recommend, the issue of adjusting the suspension for the load of your wife and gear and back to solo riding is solved. If you get a version with out ESA, is suspect you will find the rear suspension too soft...ie the stock spring rate is too low. An up graded spring rate will cost a couple of hundred or an aftermarket rear shock/spring assembly will cost $600-1100.
The R1200 duo lever/paralever is probably the best touring motorcycle suspension on the market today. There is no dive on braking, and the geometry allows better road dynamics...and some model of the 1200GS have ESA on both front and rear..unfortunately if you get a "low" r1200 you lose this dual ESA option as I understand it.
When I went true this decision process in 2010 i bought the F650GS...you F700 is better with the ESA.
Like several other have said...take them both for a ride....maybe evan a Muliti strada too.
Buy the one that makes you both smile the most