I decided to go with an urban terrain mat on which I stenciled some basic street layouts (that I don't always follow,mind). Then all of my buildings are based on 12x18 inch or 12x12 inch street thick plastic card, lighter and as strong as MDF. This lets me create new layouts rather easily. I also have a lot of rubble, brick and furniture bits I scatter about as well. Here some pictures from some of my games, from games set in Narva, Berlin and Stalingrad:
You can get scale junk and debris piles, as well as bricks and tiles from many model Train hobby stores/sites, and companies like Verlinden also make bricks in 1/48th. Bits of wooden beams you can make easily from balsa wood, painted. And from model train and dollhouse sites you can get whats called "1/2 inch" scale (aka 1/48th) model dollhouse furniture rather cheaply that adds some flavor to your game. Welcome to the Eastern Front!!