Pete said:
Personally, I think cel-shading would suit the game better (a la Paper Mario or Yoshi's Story).
Funny you should say that; neither of those even used cel-shading.
Yoshi's Story used pre-rendered sprites mapped onto pairs of polygons (IIRC, N64 doesn't have any dedicated sprite modes, or at least they're far too slow to be useful)...
And Paper Mario is regular 3D, but with vibrant colours, and the characters are also sprites mapped onto polys, but PM decided to do things differently and mapped the sprites into a real 3D space ^_^