I have sen some really beautiful floors on various forge maps, combining buildnings and other objects to make for different and new textures. Colliseum walls can be really bland, do you have any nice combination?
Well I never use the same flooring for my mini games, usually I just try to find anything that matches well together. Banks and coliseum windows look nice since the contrast eachother so much. I also like to use 1x2's.
General philosophy is to keep it as simple as possible unless I have spare objects and won't take a blow to the framerate. Emphasis on walls is more important too imo. Grass is great and keeps it fresh, and costs nothing.
If I'm making a small map or a minigame where not a lot of objects are required, I like to use platform XXLs flipped upside down, with 2x2 blocks or 2x2 banks to fill in the gaps. However, these are awkwardly-sized and somewhat hard to integrate into a map with different vertical levels; plus you end up using a whole lot of objects just to have an interesting floor. For the most part, if I'm making a larger/more complex map, I've resigned myself to coliseum walls. Here's to hoping that the next forge offers assorted large-scale objects rather than basically just one. Agreed with aPK on grass. If I build another competitive map in Reach, it's going to use a lot of natural geometry. It's just easier on budget and framerate to not have to use all those objects on a floor that Forge World can provide for you. On the other hand, a lot of grass-floor maps are very indifferently forged - it's good if you can provide some kind of apparent reason for grass to be there other than the obvious one (that it's cheaper).
For my infection map attempts I tend to use a mix of grass, 2x4's and 2x3's for the majority and then a few token objects to keep it fresh. The 2x3's and 2x4's are really useful because you can slot them together in loads of ways to make different shaped rooms. They also have a really clean, frame rate friendly design which helps a lot.
Depends what kinda map your making, in btb you almost have to use wall coliseums and grass. But I like to get really fancy in detailed maps. 2x4 is my favorite piece for flooring cause the clean dark look I'd it matches with so many other clean themed pieces.
Qft. Colly walls all the way. You can always go for the overused 2x4 block or brace large floors. Be careful with the platform floors because those can have bumps which make a big difference in minigames.
Like Mock said, sometimes you just don't have a choice in BTB/ Invasion. 4 x 4 talls, brace large's, Platform XXL's, or anything else big without lights are all nice ways to mix it up too. And of course natural terrain if it fits what you are going for.
I would go so far as saying that coli walls are almost always essential even for a 4v4 map. The only way you can truly avoid them altogether is on 1v1 and 2v2 maps (3v3, too I guess, but who builds a map specifically for that? I await the mandatory post following this one where someone says, "me!").
Basically, unless your map is open air and/or uses a lot of natural geometry for floors/walls. A map that is mostly or completely enclosed and is big enough for 4v4 pretty much requires coli walls.
Brace larges work well for floors but you kind of have to keep things scaled to a 2x4 or 4x4 block. I forged Crypt knowing I wanted brace larges as floors so you pretty much have to know what you want to do beforehand.