Corridors are rubbish. They’re just the bits between the dungeon encounters, the place where brave heroes get back into their marching order and head for the next door in the dungeon. If you’re really lucky, there will be some half-assed pit or other trap to slow down the action and give the Rogue a reason for living.
Other than that, they are nothing more that square after square of necessary but oh-so-boring dungeon tile with the occasional bend to break up the monotony.
But they don’t have to be that way.
Dungeon corridors should be a part of the adventure, and unlike your typical randomly thrown together dungeon room, They Have a Purpose. Corridors get you from A to B. They take you on a journey (even if it’s a very short one), and they should hint something about what’s coming next. A corridor leading to a Throne Room should be festooned with aged portraits of Kings past, all looking down on the adventurers with disapproving expressions. A corridor with a single blood trail down the centre hints that there’s quite possibly something Large (and possibly Still Eating) in the room ahead.
There could be shadowy alcoves in which that are Scuffling Things, and small objects discarded by past and current occupants.Corridors are your chance to add some detail and dressing to the dungeon without the players thinking “how can I use this in combat?”.
That’s not to say corridors should be nothing more than sight-seeing tours between battles. Corridors can be dangerous places where Kobolds drop oil from above, floors give way suddenly and spikes erupt from walls without warning. A corridor could be flooded (“Close the door! Quick!”), or have no clear path from one end to the other.
I would argue that the best kind of corridors are ones where the traps are obvious. Have walls lined with skeletal flailing arms, an uneven pathway across necrotic slime and flying skulls which attempt to unbalance the heroes. Make the players think “How the heck are we going to get across?”, and feel a real sense of achievement when they do.
A well designed corridor will make them want that next door, find a creative way to reach it, and give them a hint of what’s to come.
Bog standard ten foot wide dull as ditchwater corridors? Ha! No thanks.