I've found in writing adventures for Dungeon Crawl that numbering rooms tends to lead to a "one thing per room" mentality to dungeons. You can only get so much detail into a single entry before you cause your reader's eyes to glaze over; but at the same time, there needs to be more in the dungeon than answers to "what is behind this door / in this room?"
A big part of this is the idea that there are interesting things in the corridors. After all, the stereotypical old school dungeon has 10' wide corridors; my office is narrower than that. A rat's nest that is in a room could just as we'll be in a corridor; a hallway can have niches filled with statues, or hollow areas where treasure or traps are hidden. Creatures, traps and puzzles in the corridors make for a more tactically rich environment.
A lot of creature types are well suited to corridor encounters. For instance, the "cleanup crew" - slimes, oozes, jellies - make a lot of sense in corridors. Rats and other creatures of unusual size, which I've talked about in the past as much more compact than the space they're usually given, are another good choice. Non-intelligent undead make as much sense in a corridor as anywhere else; why would a lumbering zombie prefer a room? Generally opportunistic creatures should logically be in hallways.
For mobile threats, one interesting wrinkle is to make their presence a numbers game. If there is a giant rat nest in a niche of the corridor, perhaps there is only a 2 in 6 chance that the rats are there. They can go in the wandering monster list for the rest of the time.
Obviously the corridor encounters won't have non-hidden, unguarded treasure, but the possibility of hidden treasures is real. A single gem in the base of a statue can raise the stakes of a dungeon permanently, with PCs vigilantly checking every possible location for treasure, at least until they find a trapped one, and of course pit raps, arrow traps etc are natural corridor hazards.
The intrigue is in the ability of PCs to avoid encounters. These should not be in places that can't be circumvented; instead they give certain paths a higher difficulty cost. Perhaps the players find a shortcut but there are shriekers, or green slime, or another obvious challenge. Or perhaps they found an empty giant weasel nest going down a hallway; do they risk counting on it not being home on their way back?
So you'll see more of this from me in the future. I'm curious what others have done with this and what you think of the idea.