I've started a new project, and I'm trying multiple map files this time around. The last project I worked on just used one map file, so I'm not really familiar with using multiple.
What are the advantages and disadvantages of using multiple map files? Obviously multiple map files make it easier to find specific locations, rather than sifting through layers and layers of one map. What do most people use?
Multiple map files are sorted into Z levels on one map anyway, so one map with Z levels would be easier. Teleporting to different places is a lot easier when you know what map corresponds with what Z level.

I think it goes by alphabetical order, in the file tree. I just like Z levels better. :P
In response to Kaiochao (#1)
This, but I find that by using multiple map files it is much easier to sort them out, and to add new layers if you need to do so.
The first 10 z levels in my game are for the "world" so to say and are all in 1 map file. Any layer above this is for any locations in this world, and are all in a second map file. (Getting the correct z level of these maps is easy by using #define ZL 10 then using ZL + whatever the z level is displayed on the map)
The advantage of this is that if I wanted to make the world bigger I can do so easily by setting the map size of the 1st map, while keeping keeping everything organized in that the first 1-[x] levels are always the world maps, and any z level above that is always a location.

It's not particularly a major advantage, but I find that if you are going to be using a lot of z levels it will help you to keep things much more organized, which can save you a lot of headache with trying to find specific things on specific maps.
In response to The Magic Man (#2)
You could always comment a code file to tell you what's on each Z level, if you want organization.

Unfortunately, I don't comment code as much as I should.
In response to Kaiochao (#3)
True enough, but I'd still find it much easier if you knew levels 1-10 was this, instead of levels 1, 8, 12, 15, 22, 43, 48, 51, 61 and 77 were this.
(Also, I have a tendancy to "lose" parts of code, comments included. And cannot find them easily without using the search all files feature :[)
In response to Kaiochao (#3)
Unfortunately, I don't comment code as much as I should.

No one does, it takes too long. I'll leave an occasional note, though (which is like, "this list has four lists", or "///////////////////////////////////FIXXXXXXXXXXXX").
In response to The Magic Man (#2)
Instead of relying on the coordinate system you could always make use of the 'tag' variable, which allows you to tag anything and locate() based on that tag.