Hmmm... I really don't want it to look like a nicely laid out combat area with waist high walls everywhere. I just want to it look like a convincing, realistic space and then just work with what's there. It's one of the things I really appreciated about the game actually: that it didn't suffer from waist-high wall syndrome.
I'm certainly not saying they should all have waist-high walls. And only the first game really suffers from that.
Here's the video I made above of my fav fight from Uncharted 2. There are some waist-high walls, but mainly it's larger objects (which may or may not have wast-high outcrops).
There isn't a single fight in Uncharted 3 which matches that tier of level design. It looks natural, it gives the enemies as many opportunities as you, and it creates a gameplay sandbox. As I say in that video, 3 things happened there that I had never seen before. In Uncharted 3, I never see anything new. It's still a great game, but not for its combat gameplay, which is far more restrictive and sometimes poorly designed.
Edit: more specifically, you can clamber over, through and around the large bits of cover, you can climb on/hide behind the medium-sized cover, and you can hide behind the small cover. So can the enemies. And line of sight is intelligently blocked by all of these, so that enemies can lose you and sneak about and you can lose enemies and sneak about. Only one or two fights in Uncharted 3 offer these sorts of spaces where you can lose enemies, clamber about, and have dynamic encounters. They are the norm in Uncharted 2 - even on the train level which is very limited in actual volume.