Console choices

[Xiahou]

For rewarding single-player experiences:

Super Mario Galaxy (platformer)
Super Mario Galaxy 2 (ditto)
The Legend of Zelda: Twilight Princess (adventure/puzzle)
Metroid Prime Trilogy (first person shooter/adventure)
Donkey Kong Country Returns (platformer)
Okami (adventure/puzzle)
Fire Emblem: Radiant Dawn (strategy rpg)

The top four of these, though single player, do tend to be gf-friendly. Engaging experience, fun without frustrating, etc.

I'd add Cursed Mountain to that list too. A real sleeper hit for the Wii, imo. Very eerie atmosphere, and some modest scares but with accessible enough gameplay for non-hardcore types to get into.

As to PS3 vs 360, I say PS3. Free online and exclusives that are more to my tastes. Infamous 1&2, Demons Souls and Valkyria Chronicles are all amazing.