With a killhouse, you want sturdy and simple. They take alot of abuse, from weather and players. I don't know how many times I have or seen guys slip and crash into door frames and walls or climb through windows. It's alot of fun having easy access to one. Here are some pics of the one we have at the LZ. We still want to expand on it, make it bigger and have more smaller ones around it, making something like a street. http://www.pbase.com/bruce_m4/lz_sept_04&page=all
As far as bunkers go, we try and make them realistic, such as using cars, building wooden crates and stacking them (ammo dump?), 45 gallon drums (fuel dump?). We've also gotten some cinder blocks that were donated, thanx to Apoc and Sonic and made walls that kind of looked like a "bombed out" building shell.