Are you and your wife hillwalkers? If so, I'd recommend a trip round the Rhinogs. Very photogenic and usually deserted. There are some nice pics here:

Just north of Snowdon and the Glyders lie the Black Ladders (Ysgolion Duon). Evil and dripping most of the year, they too don't get the crowds.
That said, Even with the crowds I'd love to spend a day with a camera among the granite spears on top of Glyder Fach.

If you're not hillwalkers and climbers you might still enjoy things like the slate quarries at Llanberis for their pure graphic charm, and there is lots of scope for anthropology at the main climbing car parks in Llanberis and Tremadog.