Even full vector illustration programs like Illustrator, CorelDraw and Freehand have solid layer capability. I do not use layers as much in Fireworks as I do in a raster program. If I am putting together a simple diagram, with only a few objects, I will often use only one layer. In fact, if I was not writing about layers, I would have used a single layer for the image I have here. Well, maybe two, since it is nice to be able to lock your background layer in place.
Some layers practically jump up and demand to be grouped into a layer.
A menu, for example. You can lock and unlock at will as you build your document. A warning though, for those of you who come to Fireworks from a Photoshop or Paint Shop Pro background. Do not put each object onto a layer. There may be good reason to build up massive layer numbers in a raster program, but you are creating unnecessary work to use a vector program in the same way.