I've been working on a new map series recently and retrying some mapping concepts that I started to explore a year or so ago.
The idea I had back then was that it was possible to create a series of map pieces that could be snapped together in any order you wished and rearranged at will. I originally used this idea when building a tunnel driving map. I created straits, turns, downward and upward sloping sections, junctions etc... I added prefabed lights to each section and a cubemap. Then I experimented with map layouts by simply rearranging the pieces depending on how it played.
It's a fantastic way to produce reasonable looking maps quickly and it lends itself to driving sections of games where the detail can be kept low as the player will most likely pass it at high speed.
The idea of prefabricating elements of a map isn't new but I do think it's underused by many mappers preferring to build and tweak as they go.
For me personally, I like to create a playset room for each map section I create. I make walls, floors, ceilings, lights, props etc.. all in one room and then use that as a pallet to fill out my map sections. Its like a style sheet for my map and makes the whole process of creating a playable, reasonable looking map far quicker. In addition, this process also lets me ensure that the little niggles with map details are dealt with early on. For example, if my light models are lower than head height I need to set the model to be non-solid so that the player doesnt get snagged on them when playing. If I were to paste this light all over my map before fixing settings like this, I could have over 100 lights to go fix afterwards. Very time consuming.
The best thing about a playset room is that it allows you to play around with the look and feel of your map without having to recomplile a huge area.
I highly recommend it.