a daVinci with 26 inch wheels can give you the best of both worlds for touring.
Having said that, it all depends if you will stay on road surfaces 95 per cent of the time, use 700s; or, do more trail,dirt/off road, then 26" would be more logical.
We've toured 1000s of miles with 27 inch and 700c road tires/wheels. Have even used a cyclo-cross rear tire on 27" wheel, way back when, for riding 12 miles of rough dirt road with sand/rocks and mountain curves. It worked fine.
Pedal on TWOgether!
Rudy and Kay/zonatandem