Sometimes, just a small hint is enough to give players image of what's going on and give them the right feel. And perhaps help everyone remember some environmental modifiers too. This is true with the torch & light markers I made years ago, in addition to helping to remember that characters can't see everything out there.
maps and tiles
As I mentined in my post showing various terrain tiles/components, I bought Black Scroll Games' castle tiles some time ago. While the tiles look outstanding, putting castle setups with corridors was a bit clumsy. BSG's video suggests using tape, but drawing and cutting tape isn't very handy thing to do in the middle of a game.
I've spent a lot of time to browse through different rpg maps and tiles, and I thought of making a post to show a bit about what I've learned and what's available. This post doesn't go through large maps much, but there are a lot of great-looking gaming mats available. But for roleplaying purposes, tiles generally work best as they allow greatest customization possibilities.