The advantage of a pen & paper roleplaying game over a computer roleplaying game is that in a computer game only those things are possible that have been foreseen and programmed in, while in the pen & paper the players can try anything they can imagine, as long as the DM can come up with a reasonable response. Some people believe that this totally free system should also apply to combat. But playing combat in "the theater of the mind" has certain drawbacks, as every player at the table tends to have a slightly different picture in his mind, which then can lead to disagreements or lack of coordination. So many pen & paper systems have evolved towards combat rules that work best with figurines on a square grid map. If you play combat on a grid, it is evident for everybody at the table who is standing next to whom, and who is in the area of that fireball, for example. That makes a certain style of tactical combat with positioning, zones of control, and the like possible.

I recently bought a rather brilliant foldable noteboard which I added to my DM bag and plan to use whenever I get a combat for which I don't have a map prepared. But if I can prepare, I much prefer full color maps with a 1" = 5' square grid. Terrain features like obstacles providing cover or being more difficult to traverse provide some additional tactical options. And color maps just look nicer and help with immersion.

The official 4th edition Dungeons & Dragons are a mixed bag regarding maps: On the one side they often come with full color poster maps which are generally quite good. On the other side WotC is stingy with those posters, so there are just one or two of them in each adventure. Even double-sided and having more than one encounter map on each side, that doesn't cover all the encounters in the adventure. For the other encounters, the DM is on his own. WotC sometimes proposes to use their dungeon tiles, but I always found cardboard tiles to be fiddly to set up and keep together, and the standard dungeon ones are more or less just grey squares and rather ugly.

That leaves me printing my own color maps from one of two sources: Either I find the maps somebody else had made for that adventure, for example at the Cartographer's Guild. Or I create the maps myself using Campaign Cartographer / Dungeon Designer. I try to keep the map size under 22x16 squares, so that the printout fits on 4 sheets of A4 paper on my color laser printer, which I then assemble using sticky tape. Not the most durable of solutions, but usually the map only gets used during one session of the adventure.

I am not much of an artist, but with the Campaign Cartographer software even I can make pretty maps, as the software takes care of things like lighting and shadow or other effects. So sometimes I need to make a choice: Do I take a map somebody else made, or do I make my own? The Cartographer's Guild maps are often prettier than mine, but then sometimes I run into what you could call "artistic differences" with the map maker. For example frequently the artist, in order not to spoil his pretty image, leaves out or makes barely visible the square grid on the map. At which point the map loses its principal purpose: Providing a battle map for a tactical combat encounter.

On the maps I make, the grid is visible everywhere the players can go. The software allows you to specify the order in which the various layers are drawn, so I put the grid over the floor layer, but under the walls layer. The symbol layer is tricky, because I want the grid to still be visible in areas which have decorations that can be walked through, for example vegetation. But something like furniture tends to look better above the grid layer, hiding it. And then there is the question how visible to make the grid. A grid which is black or grey or white tends to be not visible in areas of the map which are of similar brightness, so the black grid disappears in the dark areas, and the white grid in the light areas. Fortunately the software allows a simple trick: I make my grid to be a thin black line, with a white "glow" effect around it. So in the light areas one can clearly see the black line, while in the dark areas the white glow keeps the line still visible.

I do love the freedom of the roleplaying in Dungeons & Dragons. But I find that not every one of my players can keep engaged with just a story all evening long. Having a fun tactical combat about half of the time keeps everybody interested in the adventure. And a good map with a nice grid helps a lot running those.