…No, seriously, you can get an awful lot of wordcount out of a door.
Part of it’s the action of getting the darn thing open. It may be stuck. It may be locked. It may be trapped. It can be all of the above. (There is a rusted door in one of the Lone Wolf gamebooks that – due to the local environment being heck nasty – can actually kill you if you can’t open it. Through combat. No, really, that’s how it works. Now that’s a door.)
And then there’s all the tension of what – or who – might be on the other side of the door. Especially the what. I imagine more than a few gamers are familiar with this scenario:
Character: “I open the door.”
DM: “You see four walls and a ceiling.”
Character: “I walk inside.”
DM: (Evil Grin) “Roll for fall damage….”
And that’s not even a monster. Oy.
So if you’re trying to up wordcount, find something that the bunnies can sink their teeth into, to raise tension, sow doubts, and get the reader guessing what will happen next. Or maybe just mentally cackling at the poor character supposedly destined to Save the World… caught in a life-or-death struggle with a door.