Eh... ask the artists... or rather, base the comparison on polygon counts from the debug. I'm not getting sucked into some console war about what things are apparent or preferable to the end user. The dense forests in Gears of War 2 (including the crowd-heavy large scale levels) and Alan Wake are heavy on polys, same with the Ninja Gaiden 2 colosseum scene. You may want to give Gears of War 2 another go because you must be forgetting a lot of the large scale environments.
Oh yeah, Gears 2 on the derricks was pretty impressive and of course the landscapes in Alan Wake.
I guess just having played Uncharted 2 recently (and I was originally a skeptic), where you have vast, extremely ornate temples or cityscapes with lots of minor details made me wonder whether the PS3 can push more geometry than the 360 - as with 360 titles like Reach though the landscapes are big they tend to be quite empty with simple geometry, the environments in Uncharted even stand out compared to the caves/ underground environments in Gears 2.
But perhaps it's just great artwork and excellent use of normal mapping?
If so, that's interesting as then the only real advantages the PS3 has over the 360 are in terms of post processing quality (like MLAA, DoF) and physics and simulation, while the 360 should have the upper hand in things like textures, geometry, shaders (except perhaps with SPU shaders) and transparencies?
I did realise of course that the Xenos was far more capable than the RSX, but I thought it was more than compensated for by the Cell and so combined the PS3 had more shading power with the only real drawbacks to the PS3 architecture being the less available, split RAM and the lack of eDRAM.
So, really the 360 suffers from a lack of AAA exclusive devs pushing the hardware? And this is basically the major reason PS3 exclusives look better, rather than the inherent capabilities of either system. (as I have always suspected)