how about drawing a side view? 

... each time to do something that has never been done... else, it is yet another Quake map...
Well, I do not have the talent of necros (as example), and I am a poor qc coder, but I am trying to innovate in each map in each part (topic, sounds, texture, etc...)

So basically, I try to put the rough architecture layout on the paper, as well as main player route (i.e SK/GK Doors, etc...) and the final fight must be epic as far as possible...
Once done, it clarifies what needs to be done, and then I start to map...
... and if I am lucky 6 month later I release my stuff.. but I guess nowadays, it will be longer, unless if I am not aiming a giant map ;) 

how about drawing a side view?

I find that harder to visualize than a top view. Also, there's more going on sideways; there's usually at least one "sideways" you can't show with a side view... 

there's usually at least one "sideways" you can't show with a side view.

So draw two side views... In most technical drawings, there's generally 2 or 3 views per layer that are
- top view
- front view
- side view

with all this you can have a good idea of what will be the 3D rendering of your stuff..

http://en.wikipedia.org/wiki/Technical_drawing#Types_of_technical_drawings for further details ;) 

I mean, you might as well just make a rudimentary version in editor. 

ya at that point if I still wanted to draw it I'd just do a perspective sketch :E 

same here, I'd rather do a perspective drawing than a side view.

It's faster to just make the stuff in the editor though.

Top down view is the one that gives the best overall view of the layout. 

top down is best for a horizontal layout. I think what metslime was driving at was that a vertical map or section of works better drawn that way.

As for doing more comlex stuff, i think a rough perspective would be most useful, and easy to do. 

I've got to try perspective sketches sometime. 

I just tend to go straight into the editor after looking at some reference shots of the kind of thing I want to make. I usually have a pretty good sense of the visual aesthetic already but things like layouts I just tend to build them as they come to mind.

Sometimes this means I have to rip up and rebuild areas as it becomes clear that they won't work, but I've never really been good at planning maps ahead of time so I just accept that it's going to happen :)

I also tried something new with my l4d2 map, I basicly finished the entire map before I even posted any screenshots online of it, as a trap I've fallen into many times before is making a really cool section of a map, getting excited about it and uploading a bunch of shots only to never work on it again. I found with the l4d2 map I had more energy to finish it the further in I got without actually showing anyone what I had made so far. Not sure why this was the case but it worked great for me! 

It's faster to just make the stuff in the editor though.

This, for me, 100%. If you just keep it rough blocks and ignore any aesthetics or detailing, you can easily block something out from scratch, and also experiment with different connections and verticality, and be able to see how it feels to move through, much more clearly than via any sort of drawing or 2d plan.