do you have a car or truck? If your wife is going to be able to help, than either is fine. I have a Hobie Oasis tandem, which is a bit heavier at 14.5 feet long. My son can't help much (yet), so I pretty much do it solo, and manage fine. Haven't popped a hernia yet, as far as I know.
The other option to consider is TWO single kayaks. You could always lash hers to yours and tow her around, if she gets tired or just wants to be pulled along like a princess.
This way, if/when you go solo, you just bring 1 yak.