Game Prep.

It's Friday afternoon, the game starts in around two hours or so, and I have to prepare.
I have the location all mapped out, I have an idea of who the bad guys are.. but I have reached a point which I know, historically, has been a weak spot of mine.
I have tended, in the past, to create lairs, dungeons or complexes in a way that seems logical and built by someone who has some idea of what they are doing.. and I have discovered that this is NOT a good method for RPG games.
Here are some of my new guidelines.

• Traps are placed in obviously places that one would suspect, and they are never of the type that only a trained rogue has any chance of disarming or disabling, also, they can always be avoided entirely with a little bit of effort.
• The lair, dungeon or what-have-you never has only one entrance/exit.
• No sliding walls, pit traps or any other kind of structure is capable of splitting the group up, unless it is for a very short period of time (and never involving combat situations).
• Much like short and memorable NPC descriptions (the guy selling the hotdogs with the huge, warty nose and pet parrot, for instance), the rooms, corridors and other features must have a short description, and the important bits are always mentioned last.. For Example, "The spacious room with the heavy oak crossbeams a foot or two above your heads, draped with thick, dusty spider webs, small, oily sconces shed flickering yellow light on a green/grey raised pool of water, so large it almost takes up all of the 20 foot square floor.. moss covers every flagstone and creeps half way up the masonry walls, it looks icky and diseased.. the murky pool smells foul and ripples on the surface indicate that there is something moving beneath the slick surface. The is a half open oak door directly across the room from you, beyond the pool."
• Boss fights happen in bad ass locations, they don't spring out at the group in the middle of a corridor or in a simple 10x10ft room.. exciting locations make for exciting fights.
• If all you players know that walking five feet above flowing magma is most certainly lethal to anyone wearing full plate, chainmail or whatever... then don't ask them to suspend their certain knowledge of real world physics and thermodynamics... magma is really, really hot, and lots of it produces some really nasty physical conditions.
• Simple things are fun.. Oozes, rust monsters, kobolds, magical swords, dragons and hoards... everyone wants to kick the door in and lay blades to the bad guys, then steal their stuff.. it is a large part of why we all play this game, after all.

There are other rules.. but for the start of tonights game, I am looking at the entrance to the dungeon and thinking "How can I make this just one entrance out of a possible group of entry/exit points?"
The answer is that I am going to have at least a couple of portals in the dungeon, the main entrance is a tricky one.. it looks like a stairwell that leads to an elevator, the elevator box has three wheels for operating a mechanism.. one makes it go up and down, the next makes a trap prime and spring on them, the third cranks down a panel and reveals a door handle, which opens the rear of the elevator to the actual corridor behind it, on the main level of the dungeon.
If the players just go down the lift, they are still in the dungeon, but have entered from a lower level.
I have decided that this is going to be a repeating design theme of the dungeon, and that the whole place is really ancient.. thousands of years.. but built big and solid, from quality materials and enchanted to withstand the weight of years.. so, lots of odd statues, strange treasures and weird room features (I mean, the Romans built rooms for vomiting after/during banquets.. what would you think that room was for if you had no idea before you walked in there?).

Anyway.. better get started.